| 1 | ---
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| 2 | title: Builtin Commands (Oils Reference)
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| 3 | all_docs_url: ..
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| 4 | body_css_class: width40
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| 5 | default_highlighter: oils-sh
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| 6 | preserve_anchor_case: yes
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| 7 | ---
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| 8 |
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| 9 | <div class="doc-ref-header">
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| 10 |
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| 11 | [Oils Reference](index.html) — Chapter **Builtin Commands**
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| 12 |
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| 13 | </div>
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| 14 |
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| 15 | This chapter in the [Oils Reference](index.html) describes builtin commands for OSH and YSH.
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| 16 |
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| 17 | <span class="in-progress">(in progress)</span>
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| 18 |
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| 19 | <div id="dense-toc">
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| 20 | </div>
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| 21 |
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| 22 | ## Memory
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| 23 |
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| 24 | ### cmd/append
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| 25 |
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| 26 | Append word arguments to a list:
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| 27 |
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| 28 | var mylist = :| hello |
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| 29 |
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| 30 | append *.py (mylist) # append all Python files
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| 31 |
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| 32 | var myflags = []
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| 33 | append -- -c 'echo hi' (myflags) # -- to avoid ambiguity
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| 34 |
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| 35 | It's a shortcut for:
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| 36 |
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| 37 | call myflags->append('-c')
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| 38 | call myflags->append('echo hi')
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| 39 |
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| 40 | Similar names: [append][]
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| 41 |
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| 42 | [append]: chap-index.html#append
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| 43 |
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| 44 | ### pp
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| 45 |
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| 46 | Pretty prints interpreter state. Some of these are implementation details,
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| 47 | subject to change.
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| 48 |
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| 49 | Examples:
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| 50 |
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| 51 | pp proc # print all procs and their doc comments
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| 52 |
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| 53 | var x = :| one two |
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| 54 | pp cell x # dump the "guts" of a cell, which is a location for a value
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| 55 |
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| 56 | pp asdl (x) # dump the ASDL "guts"
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| 57 |
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| 58 | pp line (x) # single-line stable format, for spec tests
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| 59 |
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| 60 | ## Handle Errors
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| 61 |
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| 62 | ### try
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| 63 |
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| 64 | Run a block of code, stopping at the first error. In other words, shopt
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| 65 | `errexit` is enabled.
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| 66 |
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| 67 | Set the `_status` variable to the exit status of the block, and return 0.
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| 68 |
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| 69 | try {
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| 70 | ls /nonexistent
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| 71 | }
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| 72 | if (_status !== 0) {
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| 73 | echo 'ls failed'
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| 74 | }
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| 75 |
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| 76 | Handle expression errors:
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| 77 |
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| 78 | try {
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| 79 | var x = 42 / 0
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| 80 | }
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| 81 |
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| 82 | And errors from compound commands:
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| 83 |
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| 84 | try {
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| 85 | ls | wc -l
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| 86 | diff <(sort left.txt) <(sort right.txt)
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| 87 | }
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| 88 |
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| 89 | The case statement can be useful:
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| 90 |
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| 91 | try {
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| 92 | grep PATTERN FILE.txt
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| 93 | }
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| 94 | case (_status) {
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| 95 | (0) { echo 'found' }
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| 96 | (1) { echo 'not found' }
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| 97 | (else) { echo "grep returned status $_status" }
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| 98 | }
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| 99 |
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| 100 | The `try` builtin may also set the `_error` register.
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| 101 |
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| 102 | ### boolstatus
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| 103 |
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| 104 | Runs a command and requires the exit code to be 0 or 1.
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| 105 |
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| 106 | if boolstatus egrep '[0-9]+' myfile { # may abort
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| 107 | echo 'found' # status 0 means found
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| 108 | } else {
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| 109 | echo 'not found' # status 1 means not found
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| 110 | }
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| 111 |
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| 112 | ### error
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| 113 |
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| 114 | The `error` builtin interrupts the shell program.
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| 115 |
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| 116 | error 'Missing /tmp' # program fails with status 10
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| 117 |
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| 118 | Override the default status of `10` with a named argument:
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| 119 |
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| 120 | error 'Missing /tmp' (status=99)
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| 121 |
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| 122 | In YSH, it's customary to use `error` instead of `return 1`, since it provides
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| 123 | more information:
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| 124 |
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| 125 | proc p {
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| 126 | if ! test -d /tmp {
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| 127 | error 'Missing /tmp' # more descriptive than return
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| 128 | }
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| 129 | echo hi
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| 130 | }
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| 131 |
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| 132 | Handle the error with the `try` builtin:
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| 133 |
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| 134 | try {
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| 135 | p
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| 136 | }
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| 137 | if (_status !== 0) {
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| 138 | echo $[_error.message] # => Missing /tmp
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| 139 | }
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| 140 |
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| 141 | The integer `_status` is always set, and the Dict `_error` is set for all
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| 142 | "structured" errors, which includes errors raised by the `try` builtin.
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| 143 |
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| 144 | Special properties of `_error`:
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| 145 |
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| 146 | - `_error.message` - the positional string arg
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| 147 | - `_error.status` - the named `status` arg, or the default 10
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| 148 |
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| 149 | You can attach other, arbitrary properties to the error:
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| 150 |
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| 151 | error 'Oops' (path='foo.json')
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| 152 |
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| 153 | They are attached to `_error`:
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| 154 |
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| 155 | try {
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| 156 | error 'Oops' (path='foo.json')
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| 157 | }
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| 158 | if (_status !== 0) {
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| 159 | echo $[_error.path] # => foo.json
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| 160 | }
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| 161 |
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| 162 | ## Shell State
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| 163 |
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| 164 | ### ysh-cd
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| 165 |
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| 166 | It takes a block:
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| 167 |
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| 168 | cd / {
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| 169 | echo $PWD
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| 170 | }
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| 171 |
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| 172 | ### ysh-shopt
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| 173 |
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| 174 | It takes a block:
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| 175 |
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| 176 | shopt --unset errexit {
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| 177 | false
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| 178 | echo 'ok'
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| 179 | }
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| 180 |
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| 181 | ### shvar
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| 182 |
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| 183 | Execute a block with a global variable set.
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| 184 |
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| 185 | shvar IFS=/ {
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| 186 | echo "ifs is $IFS"
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| 187 | }
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| 188 | echo "ifs restored to $IFS"
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| 189 |
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| 190 | ### ctx
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| 191 |
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| 192 | Execute a block with a shared "context" that can be updated using the `ctx`
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| 193 | built-in.
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| 194 |
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| 195 | var mydict = {}
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| 196 | ctx push (mydict) {
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| 197 | # = mydict => {}
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| 198 | ctx set (mykey='myval')
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| 199 | }
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| 200 | # = mydict => { mykey: 'myval' }
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| 201 |
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| 202 | The context can be modified with `ctx set (key=val)`, which updates or inserts
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| 203 | the value at the given key.
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| 204 |
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| 205 | The context can also be updated with `ctx emit field (value)`.
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| 206 |
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| 207 | ctx push (mydict) {
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| 208 | # = mydict => {}
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| 209 | ctx emit mylist (0)
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| 210 | # = mydict => { mylist: [0] }
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| 211 | ctx emit mylist (1)
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| 212 | }
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| 213 | # = mydict => { mylist: [0, 1] }
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| 214 |
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| 215 | Contexts can be nested, resulting in a stack of contexts.
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| 216 |
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| 217 | ctx push (mydict1) {
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| 218 | ctx set (dict=1)
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| 219 | ctx push (mydict2) {
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| 220 | ctx set (dict=2)
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| 221 | }
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| 222 | }
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| 223 | # = mydict1 => { dict: 1 }
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| 224 | # = mydict2 => { dict: 2 }
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| 225 |
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| 226 | `ctx` is useful for creating DSLs, such as a mini-parseArgs.
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| 227 |
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| 228 | proc parser (; place ; ; block_def) {
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| 229 | var p = {}
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| 230 | ctx push (p, block_def)
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| 231 | call place->setValue(p)
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| 232 | }
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| 233 |
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| 234 | proc flag (short_name, long_name; type; help) {
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| 235 | ctx emit flag ({short_name, long_name, type, help})
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| 236 | }
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| 237 |
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| 238 | proc arg (name) {
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| 239 | ctx emit arg ({name})
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| 240 | }
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| 241 |
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| 242 | parser (&spec) {
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| 243 | flag -t --tsv (Bool, help='Output as TSV')
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| 244 | flag -r --recursive (Bool, help='Recurse into the given directory')
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| 245 | flag -N --count (Int, help='Process no more than N files')
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| 246 | arg path
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| 247 | }
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| 248 |
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| 249 | ### push-registers
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| 250 |
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| 251 | Save global registers like $? on a stack. It's useful for preventing plugins
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| 252 | from interfering with user code. Example:
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| 253 |
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| 254 | status_42 # returns 42 and sets $?
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| 255 | push-registers { # push a new frame
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| 256 | status_43 # top of stack changed here
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| 257 | echo done
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| 258 | } # stack popped
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| 259 | echo $? # 42, read from new top-of-stack
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| 260 |
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| 261 | Current list of registers:
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| 262 |
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| 263 | Regex data underlying BASH_REMATCH, _group(), _start(), _end()
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| 264 | $?
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| 265 | _status # set by the try builtin
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| 266 | PIPESTATUS # aka _pipeline_status
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| 267 | _process_sub_status
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| 268 |
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| 269 |
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| 270 | ## Modules
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| 271 |
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| 272 | ### runproc
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| 273 |
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| 274 | Runs a named proc with the given arguments. It's often useful as the only top
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| 275 | level statement in a "task file":
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| 276 |
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| 277 | proc p {
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| 278 | echo hi
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| 279 | }
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| 280 | runproc @ARGV
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| 281 |
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| 282 | Like 'builtin' and 'command', it affects the lookup of the first word.
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| 283 |
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| 284 | ### module
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| 285 |
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| 286 | Registers a name in the global module dict. Returns 0 if it doesn't exist, or
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| 287 | 1 if it does.
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| 288 |
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| 289 | Use it like this in executable files:
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| 290 |
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| 291 | module main || return 0
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| 292 |
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| 293 | And like this in libraries:
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| 294 |
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| 295 | module myfile.ysh || return 0
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| 296 |
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| 297 | ### is-main
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| 298 |
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| 299 | The `is-main` builtin returns 1 (false) if the current file was executed with
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| 300 | the `source` builtin.
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| 301 |
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| 302 | In the "main" file, including `-c` or `stdin` input, it returns 0 (true).
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| 303 |
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| 304 | Use it like this:
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| 305 |
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| 306 | if is-main {
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| 307 | runproc @ARGV
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| 308 | }
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| 309 |
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| 310 | ### use
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| 311 |
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| 312 | TODO
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| 313 |
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| 314 | Reuse code from other files, respecting namespaces.
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| 315 |
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| 316 | use lib/foo.ysh # relative import, i.ie implicit $_this_dir?
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| 317 | # makes name 'foo' available
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| 318 |
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| 319 | Bind a specific name:
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| 320 |
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| 321 | use lib/foo.ysh (&myvar) # makes 'myvar' available
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| 322 |
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| 323 | Bind multiple names:
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| 324 |
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| 325 | use lib/foo.ysh (&myvar) {
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| 326 | var log, die
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| 327 | }
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| 328 |
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| 329 | Maybe:
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| 330 |
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| 331 | use lib/foo.ysh (&myvar) {
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| 332 | var mylog = myvar.log
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| 333 | }
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| 334 |
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| 335 | Also a declaration
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| 336 |
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| 337 | use --extern grep sed
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| 338 |
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| 339 | ## I/O
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| 340 |
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| 341 | ### ysh-read
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| 342 |
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| 343 | YSH adds long flags to shell's `read`:
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| 344 |
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| 345 | read --all # whole file including newline, fills $_reply
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| 346 | read --all (&x) # fills $x
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| 347 |
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| 348 | read --num-bytes 3 # read N bytes, fills _reply
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| 349 | read --num-bytes 3 (&x) # fills $x
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| 350 |
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| 351 | And a convenience:
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| 352 |
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| 353 | read -0 # read until NUL, synonym for read -r -d ''
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| 354 |
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| 355 | TODO: We used to have `read --line`, but buffered I/O doesn't mix with shell
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| 356 | I/O, which is reads directly from file descriptors.
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| 357 |
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| 358 | <!--
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| 359 |
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| 360 | buffered, line-oriented I/O
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| 361 |
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| 362 | read --line # fills $_reply var with line
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| 363 | read --line (&x) # fills $x (&x is a place)
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| 364 |
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| 365 | read --line --with-eol # keep the \n
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| 366 |
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| 367 | You may want to use `fromJ8()` or `fromJson()` after reading a line.
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| 368 |
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| 369 | TODO: read --netstr
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| 370 | -->
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| 371 |
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| 372 | <!--
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| 373 |
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| 374 | Problem with read --json -- there's also https://jsonlines.org, which allows
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| 375 |
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| 376 | {"my": "line"}
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| 377 |
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| 378 | That can be done with
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| 379 |
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| 380 | while read --line {
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| 381 | var record = fromJson(_reply)
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| 382 | }
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| 383 |
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| 384 | This is distinct from:
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| 385 |
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| 386 | while read --line --j8 {
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| 387 | echo $_reply
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| 388 | }
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| 389 |
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| 390 | This allows unquoted. Maybe it should be read --j8-line
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| 391 |
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| 392 | What about write? These would be the same:
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| 393 |
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| 394 | write --json -- $s
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| 395 | write --j8 -- $s
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| 396 |
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| 397 | write -- $[toJson(s)]
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| 398 | write -- $[toJson8(s)]
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| 399 |
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| 400 | write --json -- @strs
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| 401 | write --j8 -- @strs
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| 402 |
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| 403 | write -- @[toJson(s) for s in strs]
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| 404 | write -- @[toJson8(s) for s in strs]
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| 405 |
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| 406 | It's an argument for getting rid --json and --j8? I already implemented them,
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| 407 | but it makes the API smaller.
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| 408 |
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| 409 | I guess the main thing would be to AVOID quoting sometimes?
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| 410 |
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| 411 | $ write --j8 -- unquoted
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| 412 | unquoted
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| 413 |
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| 414 | $ write --j8 -- $'\'' '"'
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| 415 | "'"
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| 416 | "\""
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| 417 |
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| 418 | I think this could be the shell style?
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| 419 |
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| 420 | $ write --shell-str -- foo bar baz
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| 421 |
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| 422 | Or it could be
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| 423 |
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| 424 | $ write -- @[toShellString(s) for s in strs]
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| 425 |
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| 426 | I want this to be "J8 Lines", but it can be done in pure YSH. It's not built
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| 427 | into the interpreter.
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| 428 |
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| 429 | foo/bar
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| 430 | "hi"
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| 431 | b'hi'
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| 432 | u'hi'
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| 433 |
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| 434 | But what about
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| 435 |
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| 436 | Fool's Gold
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| 437 | a'hi' # This feels like an error?
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| 438 | a"hi" # what about this?
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| 439 |
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| 440 | Technically we CAN read those as literal strings
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| 441 | -->
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| 442 |
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| 443 | ### ysh-echo
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| 444 |
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| 445 | Print arguments to stdout, separated by a space.
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| 446 |
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| 447 | ysh$ echo hi there
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| 448 | hi there
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| 449 |
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| 450 | The [simple_echo][] option means that flags aren't accepted, and `--` is not
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| 451 | accepted.
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| 452 |
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| 453 | ysh$ echo -n
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| 454 | -n
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| 455 |
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| 456 | See the [YSH FAQ][echo-en] for details.
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| 457 |
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| 458 | [simple_echo]: chap-option.html#ysh:all
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| 459 | [echo-en]: ../ysh-faq.html#how-do-i-write-the-equivalent-of-echo-e-or-echo-n
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| 460 |
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| 461 | ### write
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| 462 |
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| 463 | write fixes problems with shell's `echo` builtin.
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| 464 |
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| 465 | The default separator is a newline, and the default terminator is a
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| 466 | newline.
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| 467 |
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| 468 | Examples:
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| 469 |
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| 470 | write -- ale bean # write two lines
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| 471 |
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| 472 | write -n -- ale bean # synonym for --end '', like echo -n
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| 473 | write --sep '' --end '' -- a b # write 2 bytes
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| 474 | write --sep $'\t' --end $'\n' -- a b # TSV line
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| 475 |
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| 476 | You may want to use `toJson8()` or `toJson()` before writing:
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| 477 |
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| 478 | write -- $[toJson8(mystr)]
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| 479 | write -- $[toJson(mystr)]
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| 480 |
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| 481 |
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| 482 | <!--
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| 483 | write --json -- ale bean # JSON encode, guarantees two lines
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| 484 | write --j8 -- ale bean # J8 encode, guarantees two lines
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| 485 | -->
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| 486 |
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| 487 |
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| 488 | ### fork
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| 489 |
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| 490 | Run a command, but don't wait for it to finish.
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| 491 |
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| 492 | fork { sleep 1 }
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| 493 | wait -n
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| 494 |
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| 495 | In YSH, use `fork` rather than shell's `&` ([ampersand][]).
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| 496 |
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| 497 | [ampersand]: chap-cmd-lang.html#ampersand
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| 498 |
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| 499 | ### forkwait
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| 500 |
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| 501 | The preferred alternative to shell's `()`. Prefer `cd` with a block if possible.
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| 502 |
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| 503 | forkwait {
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| 504 | not_mutated=zzz
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| 505 | }
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| 506 | echo $not_mutated
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| 507 |
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| 508 | ### fopen
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| 509 |
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| 510 | Runs a block passed to it. It's designed so redirects have a **prefix**
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| 511 | syntax:
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| 512 |
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| 513 | fopen >out.txt {
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| 514 | echo 1
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| 515 | echo 2
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| 516 | }
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| 517 |
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| 518 | Rather than shell style:
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| 519 |
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| 520 | { echo 1
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| 521 | echo 2
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| 522 | } >out.txt
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| 523 |
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| 524 | When a block is long, the former is more readable.
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| 525 |
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| 526 | ## Hay Config
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| 527 |
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| 528 | ### hay
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| 529 |
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| 530 | ### haynode
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| 531 |
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| 532 |
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| 533 | ## Data Formats
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| 534 |
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| 535 | ### json
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| 536 |
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| 537 | Write JSON:
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| 538 |
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| 539 | var d = {name: 'bob', age: 42}
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| 540 | json write (d) # default indentation of 2
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| 541 | json write (d, space=0) # no indentation
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| 542 |
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| 543 | Read JSON:
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| 544 |
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| 545 | echo hi | json read # fills $_reply by default
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| 546 |
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| 547 | Or use an explicit place:
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| 548 |
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| 549 | var x = ''
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| 550 | json read (&x) < myfile.txt
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| 551 |
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| 552 | Related: [err-json-encode][] and [err-json-decode][]
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| 553 |
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| 554 | [err-json-encode]: chap-errors.html#err-json-encode
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| 555 | [err-json-decode]: chap-errors.html#err-json-decode
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| 556 |
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| 557 | ### json8
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| 558 |
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| 559 | Like `json`, but on the encoding side:
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| 560 |
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| 561 | - Falls back to `b'\yff'` instead of lossy Unicode replacement char
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| 562 |
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| 563 | On decoding side:
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| 564 |
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| 565 | - Understands `b'' u''` strings
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| 566 |
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| 567 | Related: [err-json8-encode]() and [err-json8-decode]()
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| 568 |
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| 569 | [err-json8-encode]: chap-errors.html#err-json8-encode
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| 570 | [err-json8-decode]: chap-errors.html#err-json8-decode
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| 571 |
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| 572 | ## Testing
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| 573 |
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| 574 | TODO: describe
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| 575 |
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| 576 | ## External Lang
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| 577 |
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| 578 | TODO: when
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| 579 |
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| 580 |
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| 581 | ## I/O
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| 582 |
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| 583 | These builtins take input and output. They're often used with redirects.
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| 584 |
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| 585 | ### read
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| 586 |
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| 587 | read FLAG* VAR*
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| 588 |
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| 589 | Read a line from stdin, split it into tokens with the `$IFS` algorithm,
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| 590 | and assign the tokens to the given variables. When no VARs are given,
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| 591 | assign to `$REPLY`.
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| 592 |
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| 593 | Note: When writing ySH, prefer the extensions documented in
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| 594 | [ysh-read](#ysh-read). The `read` builtin is confusing because `-r` needs to
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| 595 | be explicitly enabled.
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| 596 |
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| 597 | Flags:
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| 598 |
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| 599 | -a ARRAY assign the tokens to elements of this array
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| 600 | -d CHAR use DELIM as delimiter, instead of newline
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| 601 | -n NUM read up to NUM characters, respecting delimiters
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| 602 | -p STR print the string PROMPT before reading input
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| 603 | -r raw mode: don't let backslashes escape characters
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| 604 | -s silent: do not echo input coming from a terminal
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| 605 | -t NUM time out and fail after TIME seconds
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| 606 | -t 0 returns whether any input is available
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| 607 | -u FD read from file descriptor FD instead of 0 (stdin)
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| 608 |
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| 609 | <!-- -N NUM read up to NUM characters, ignoring delimiters -->
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| 610 | <!-- -e use readline to obtain the line
|
| 611 | -i STR use STR as the initial text for readline -->
|
| 612 |
|
| 613 | ### echo
|
| 614 |
|
| 615 | echo FLAG* ARG*
|
| 616 |
|
| 617 | Prints ARGs to stdout, separated by a space, and terminated by a newline.
|
| 618 |
|
| 619 | Flags:
|
| 620 |
|
| 621 | -e enable interpretation of backslash escapes
|
| 622 | -n omit the trailing newline
|
| 623 | <!-- -E -->
|
| 624 |
|
| 625 | See [char-escapes](chap-mini-lang.html#char-escapes).
|
| 626 |
|
| 627 | ### printf
|
| 628 |
|
| 629 | printf FLAG* FMT ARG*
|
| 630 |
|
| 631 | Formats values and prints them. The FMT string contain three types of objects:
|
| 632 |
|
| 633 | 1. Literal Characters
|
| 634 | 2. Character escapes like `\t`. See [char-escapes](chap-mini-lang.html#char-escapes).
|
| 635 | 3. Percent codes like `%s` that specify how to format each each ARG.
|
| 636 |
|
| 637 | If not enough ARGS are passed, the empty string is used. If too many are
|
| 638 | passed, the FMT string will be "recycled".
|
| 639 |
|
| 640 | Flags:
|
| 641 |
|
| 642 | -v VAR Write output in variable VAR instead of standard output.
|
| 643 |
|
| 644 | Format specifiers:
|
| 645 |
|
| 646 | %% Prints a single "%".
|
| 647 | %b Interprets backslash escapes while printing.
|
| 648 | %q Prints the argument escaping the characters needed to make it reusable
|
| 649 | as shell input.
|
| 650 | %d Print as signed decimal number.
|
| 651 | %i Same as %d.
|
| 652 | %o Print as unsigned octal number.
|
| 653 | %u Print as unsigned decimal number.
|
| 654 | %x Print as unsigned hexadecimal number with lower-case hex-digits (a-f).
|
| 655 | %X Same as %x, but with upper-case hex-digits (A-F).
|
| 656 | %f Print as floating point number.
|
| 657 | %e Print as a double number, in "±e" format (lower-case e).
|
| 658 | %E Same as %e, but with an upper-case E.
|
| 659 | %g Interprets the argument as double, but prints it like %f or %e.
|
| 660 | %G Same as %g, but print it like %E.
|
| 661 | %c Print as a single char, only the first character is printed.
|
| 662 | %s Print as string
|
| 663 | %n The number of characters printed so far is stored in the variable named
|
| 664 | in the argument.
|
| 665 | %a Interprets the argument as double, and prints it like a C99 hexadecimal
|
| 666 | floating-point literal.
|
| 667 | %A Same as %a, but print it like %E.
|
| 668 | %(FORMAT)T Prints date and time, according to FORMAT as a format string
|
| 669 | for strftime(3). The argument is the number of seconds since
|
| 670 | epoch. It can also be -1 (current time, also the default value
|
| 671 | if there is no argument) or -2 (shell startup time).
|
| 672 |
|
| 673 | ### readarray
|
| 674 |
|
| 675 | Alias for `mapfile`.
|
| 676 |
|
| 677 | ### mapfile
|
| 678 |
|
| 679 | mapfile FLAG* ARRAY?
|
| 680 |
|
| 681 | Reads lines from stdin into the variable named ARRAY (default
|
| 682 | `${MAPFILE[@]}`).
|
| 683 |
|
| 684 | Flags:
|
| 685 |
|
| 686 | -t Remove the trailing newline from every line
|
| 687 | <!--
|
| 688 | -d CHAR use CHAR as delimiter, instead of the default newline
|
| 689 | -n NUM copy up to NUM lines
|
| 690 | -O NUM begins copying lines at the NUM element of the array
|
| 691 | -s NUM discard the first NUM lines
|
| 692 | -u FD read from FD file descriptor instead of the standard input
|
| 693 | -C CMD run CMD every NUM lines specified in -c
|
| 694 | -c NUM every NUM lines, the CMD command in C will be run
|
| 695 | -->
|
| 696 |
|
| 697 | ## Run Code
|
| 698 |
|
| 699 | These builtins accept shell code and run it.
|
| 700 |
|
| 701 | ### source
|
| 702 |
|
| 703 | source SCRIPT ARG*
|
| 704 |
|
| 705 | Executes SCRIPT with given ARGs in the context of the current shell. It will
|
| 706 | modify existing variables.
|
| 707 |
|
| 708 | ### eval
|
| 709 |
|
| 710 | eval ARG+
|
| 711 |
|
| 712 | Creates a string by joining ARGs with a space, then runs it as a shell command.
|
| 713 |
|
| 714 | Example:
|
| 715 |
|
| 716 | # Create the string echo "hello $name" and run it.
|
| 717 | a='echo'
|
| 718 | b='"hello $name"'
|
| 719 | eval $a $b
|
| 720 |
|
| 721 | Tips:
|
| 722 |
|
| 723 | - Using `eval` can confuse code and user-supplied data, leading to [security
|
| 724 | issues][].
|
| 725 | - Prefer passing single string ARG to `eval`.
|
| 726 |
|
| 727 | [security issues]: https://mywiki.wooledge.org/BashFAQ/048
|
| 728 |
|
| 729 | YSH eval:
|
| 730 |
|
| 731 | var myblock = ^(echo hi)
|
| 732 | eval (myblock) # => hi
|
| 733 |
|
| 734 |
|
| 735 | ### trap
|
| 736 |
|
| 737 | trap FLAG* CMD SIGNAL*
|
| 738 |
|
| 739 | Registers the shell string CMD to be run after the SIGNALs are received. If
|
| 740 | the CMD is empty, then the signal is ignored.
|
| 741 |
|
| 742 | Flags:
|
| 743 |
|
| 744 | -l Lists all signals and their signal number
|
| 745 | -p Prints a list of the installed signal handlers
|
| 746 |
|
| 747 | Tip:
|
| 748 |
|
| 749 | Prefer passing the name of a shell function to `trap`.
|
| 750 |
|
| 751 | ## Set Options
|
| 752 |
|
| 753 | The `set` and `shopt` builtins set global shell options. YSH code should use
|
| 754 | the more natural `shopt`.
|
| 755 |
|
| 756 | ### set
|
| 757 |
|
| 758 | set FLAG* ARG*
|
| 759 |
|
| 760 | Sets global shell options. Short style:
|
| 761 |
|
| 762 | set -e
|
| 763 |
|
| 764 | Long style:
|
| 765 |
|
| 766 | set -o errexit
|
| 767 |
|
| 768 | Set the arguments array:
|
| 769 |
|
| 770 | set -- 1 2 3
|
| 771 |
|
| 772 | ### shopt
|
| 773 |
|
| 774 | shopt FLAG* OPTION* BLOCK?
|
| 775 |
|
| 776 | Sets global shell options.
|
| 777 |
|
| 778 | Flags:
|
| 779 |
|
| 780 | -s --set Turn the named options on
|
| 781 | -u --unset Turn the named options off
|
| 782 | -p Print option values
|
| 783 | -q Return 0 if the option is true, else 1
|
| 784 |
|
| 785 | Examples:
|
| 786 |
|
| 787 | shopt --set errexit
|
| 788 |
|
| 789 | You can set or unset multiple options with the groups `strict:all`,
|
| 790 | `ysh:upgrade`, and `ysh:all`.
|
| 791 |
|
| 792 | If a block is passed, then the mutated options are pushed onto a stack, the
|
| 793 | block is executed, and then options are restored to their original state.
|
| 794 |
|
| 795 | ## Working Dir
|
| 796 |
|
| 797 | These 5 builtins deal with the working directory of the shell.
|
| 798 |
|
| 799 | ### cd
|
| 800 |
|
| 801 | cd FLAG* DIR
|
| 802 |
|
| 803 | Changes the working directory of the current shell process to DIR.
|
| 804 |
|
| 805 | If DIR isn't specified, change to `$HOME`. If DIR is `-`, change to `$OLDPWD`
|
| 806 | (a variable that the sets to the previous working directory.)
|
| 807 |
|
| 808 | Flags:
|
| 809 |
|
| 810 | -L Follow symbolic links, i.e. change to the TARGET of the symlink.
|
| 811 | (default).
|
| 812 | -P Don't follow symbolic links.
|
| 813 |
|
| 814 | ### pwd
|
| 815 |
|
| 816 | pwd FLAG*
|
| 817 |
|
| 818 | Prints the current working directory.
|
| 819 |
|
| 820 | Flags:
|
| 821 |
|
| 822 | -L Follow symbolic links if present (default)
|
| 823 | -P Don't follow symbolic links. Print the link instead of the target.
|
| 824 |
|
| 825 | ### pushd
|
| 826 |
|
| 827 | <!--pushd FLAGS DIR-->
|
| 828 | pushd DIR
|
| 829 | <!--pushd +/-NUM-->
|
| 830 |
|
| 831 | Add DIR to the directory stack, then change the working directory to DIR.
|
| 832 | Typically used with `popd` and `dirs`.
|
| 833 |
|
| 834 | <!--FLAGS:
|
| 835 | -n Don't change the working directory, just manipulate the stack
|
| 836 | NUM:
|
| 837 | Rotates the stack the number of places specified. Eg, given the stack
|
| 838 | '/foo /bar /baz', where '/foo' is the top of the stack, pushd +1 will move
|
| 839 | it to the bottom, '/bar /baz /foo'-->
|
| 840 |
|
| 841 | ### popd
|
| 842 |
|
| 843 | popd
|
| 844 |
|
| 845 | Removes a directory from the directory stack, and changes the working directory
|
| 846 | to it. Typically used with `pushd` and `dirs`.
|
| 847 |
|
| 848 | ### dirs
|
| 849 |
|
| 850 | dirs FLAG*
|
| 851 |
|
| 852 | Shows the contents of the directory stack. Typically used with `pushd` and
|
| 853 | `popd`.
|
| 854 |
|
| 855 | Flags:
|
| 856 |
|
| 857 | -c Clear the dir stack.
|
| 858 | -l Show the dir stack, but with the real path instead of ~.
|
| 859 | -p Show the dir stack, but formatted as one line per entry.
|
| 860 | -v Like -p, but numbering each line.
|
| 861 |
|
| 862 | ## Completion
|
| 863 |
|
| 864 | These builtins implement our bash-compatible autocompletion system.
|
| 865 |
|
| 866 | ### complete
|
| 867 |
|
| 868 | Registers completion policies for different commands.
|
| 869 |
|
| 870 | ### compgen
|
| 871 |
|
| 872 | Generates completion candidates inside a user-defined completion function.
|
| 873 |
|
| 874 | It can also be used in scripts, i.e. outside a completion function.
|
| 875 |
|
| 876 | ### compopt
|
| 877 |
|
| 878 | Changes completion options inside a user-defined completion function.
|
| 879 |
|
| 880 | ### compadjust
|
| 881 |
|
| 882 | Adjusts `COMP_ARGV` according to specified delimiters, and optionally set
|
| 883 | variables cur, prev, words (an array), and cword. May also set 'split'.
|
| 884 |
|
| 885 | This is an OSH extension that makes it easier to run the bash-completion
|
| 886 | project.
|
| 887 |
|
| 888 | ### compexport
|
| 889 |
|
| 890 | Complete an entire shell command string. For example,
|
| 891 |
|
| 892 | compexport -c 'echo $H'
|
| 893 |
|
| 894 | will complete variables like `$HOME`. And
|
| 895 |
|
| 896 | compexport -c 'ha'
|
| 897 |
|
| 898 | will complete builtins like `hay`, as well as external commands.
|
| 899 |
|
| 900 |
|
| 901 | ## Shell Process
|
| 902 |
|
| 903 | These builtins mutate the state of the shell process.
|
| 904 |
|
| 905 | ### exec
|
| 906 |
|
| 907 | exec BIN_PATH ARG*
|
| 908 |
|
| 909 | Replaces the running shell with the binary specified, which is passed ARGs.
|
| 910 | BIN_PATH must exist on the file system; i.e. it can't be a shell builtin or
|
| 911 | function.
|
| 912 |
|
| 913 | ### umask
|
| 914 |
|
| 915 | umask MODE?
|
| 916 |
|
| 917 | Sets the bit mask that determines the permissions for new files and
|
| 918 | directories. The mask is subtracted from 666 for files and 777 for
|
| 919 | directories.
|
| 920 |
|
| 921 | Oils currently supports writing masks in octal.
|
| 922 |
|
| 923 | If no MODE, show the current mask.
|
| 924 |
|
| 925 | ### ulimit
|
| 926 |
|
| 927 | ulimit --all
|
| 928 | ulimit -a
|
| 929 | ulimit FLAGS* -RESOURCE_FLAG VALUE?
|
| 930 |
|
| 931 | ulimit FLAGS* VALUE? # discouraged
|
| 932 |
|
| 933 | Show and modify process resource limits.
|
| 934 |
|
| 935 | Flags:
|
| 936 |
|
| 937 | -S for soft limit
|
| 938 | -H for hard limit
|
| 939 |
|
| 940 | -c -d -f ... # ulimit --all shows all resource flags
|
| 941 |
|
| 942 | Show a table of resources:
|
| 943 |
|
| 944 | ulimit --all
|
| 945 | ulimit -a
|
| 946 |
|
| 947 | For example, the table shows that `-n` is the flag that controls the number
|
| 948 | file descriptors, the soft and hard limit for `-n`, and the multiplication
|
| 949 | "factor" for the integer VALUE you pass.
|
| 950 |
|
| 951 | ---
|
| 952 |
|
| 953 | Here are examples of using resource flags.
|
| 954 |
|
| 955 | Get the soft limit for the number of file descriptors:
|
| 956 |
|
| 957 | ulimit -S -n
|
| 958 | ulimit -n # same thing
|
| 959 |
|
| 960 | Get the hard limit:
|
| 961 |
|
| 962 | ulimit -H -n
|
| 963 |
|
| 964 | Set the soft or hard limit:
|
| 965 |
|
| 966 | ulimit -S -n 100
|
| 967 | ulimit -H -n 100
|
| 968 |
|
| 969 | Set both limits:
|
| 970 |
|
| 971 | ulimit -n 100
|
| 972 |
|
| 973 | A special case that's discouraged: with no resource flag, `-f` is assumed:
|
| 974 |
|
| 975 | ulimit # equivalent to ulimit -f
|
| 976 | ulimit 100 # equivalent to ulimit -f 100
|
| 977 |
|
| 978 | ### times
|
| 979 |
|
| 980 | times
|
| 981 |
|
| 982 | Shows the user and system time used by the shell and its child processes.
|
| 983 |
|
| 984 | ## Child Process
|
| 985 |
|
| 986 | ### jobs
|
| 987 |
|
| 988 | jobs
|
| 989 |
|
| 990 | Shows all jobs running in the shell and their status.
|
| 991 |
|
| 992 | ### wait
|
| 993 |
|
| 994 | wait FLAG* ARG
|
| 995 |
|
| 996 | Wait for processes to exit.
|
| 997 |
|
| 998 | If the ARG is a PID, wait only for that job, and return its status.
|
| 999 |
|
| 1000 | If there's no ARG, wait for all child processes.
|
| 1001 |
|
| 1002 | <!--
|
| 1003 | The ARG can be a PID (tracked by the kernel), or a job number (tracked by the
|
| 1004 | shell). Specify jobs with the syntax `%jobnumber`.
|
| 1005 | -->
|
| 1006 |
|
| 1007 | Flags:
|
| 1008 |
|
| 1009 | -n Wait for the next process to exit, rather than a specific process.
|
| 1010 |
|
| 1011 | Wait can be interrupted by a signal, in which case the exit code indicates the
|
| 1012 | signal number.
|
| 1013 |
|
| 1014 | ### fg
|
| 1015 |
|
| 1016 | fg JOB?
|
| 1017 |
|
| 1018 | Returns a job running in the background to the foreground. If no JOB is
|
| 1019 | specified, use the latest job.
|
| 1020 |
|
| 1021 | <!--<h4 id="bg">bg</h4>
|
| 1022 |
|
| 1023 | The bg builtin resumes suspend job, while keeping it in the background.
|
| 1024 |
|
| 1025 | bg JOB?
|
| 1026 |
|
| 1027 | JOB:
|
| 1028 | Job ID to be resumed in the background. If none is specified, the latest job
|
| 1029 | is chosen. -->
|
| 1030 |
|
| 1031 | ## External
|
| 1032 |
|
| 1033 | ### test
|
| 1034 |
|
| 1035 | test OP ARG
|
| 1036 | test ARG OP ARG
|
| 1037 | [ OP ARG ] # [ is an alias for test that requires closing ]
|
| 1038 | [ ARG OP ARG ]
|
| 1039 |
|
| 1040 | Evaluates a conditional expression and returns 0 (true) or 1 (false).
|
| 1041 |
|
| 1042 | Note that [ is the name of a builtin, not an operator in the language. Use
|
| 1043 | 'test' to avoid this confusion.
|
| 1044 |
|
| 1045 | String expressions:
|
| 1046 |
|
| 1047 | -n STR True if STR is not empty.
|
| 1048 | 'test STR' is usually equivalent, but discouraged.
|
| 1049 | -z STR True if STR is empty.
|
| 1050 | STR1 = STR2 True if the strings are equal.
|
| 1051 | STR1 != STR2 True if the strings are not equal.
|
| 1052 | STR1 < STR2 True if STR1 sorts before STR2 lexicographically.
|
| 1053 | STR1 > STR2 True if STR1 sorts after STR2 lexicographically.
|
| 1054 | Note: < and > should be quoted like \< and \>
|
| 1055 |
|
| 1056 | File expressions:
|
| 1057 |
|
| 1058 | -a FILE Synonym for -e.
|
| 1059 | -b FILE True if FILE is a block special file.
|
| 1060 | -c FILE True if FILE is a character special file.
|
| 1061 | -d FILE True if FILE is a directory.
|
| 1062 | -e FILE True if FILE exists.
|
| 1063 | -f FILE True if FILE is a regular file.
|
| 1064 | -g FILE True if FILE has the sgid bit set.
|
| 1065 | -G FILE True if current user's group is also FILE's group.
|
| 1066 | -h FILE True if FILE is a symbolic link.
|
| 1067 | -L FILE True if FILE is a symbolic link.
|
| 1068 | -k FILE True if FILE has the sticky bit set.
|
| 1069 | -O FILE True if current user is the file owner.
|
| 1070 | -p FILE True if FILE is a named pipe (FIFO).
|
| 1071 | -r FILE True if FILE is readable.
|
| 1072 | -s FILE True if FILE has size bigger than 0.
|
| 1073 | -S FILE True if FILE is a socket file.
|
| 1074 | -t FD True if file descriptor FD is open and refers to a terminal.
|
| 1075 | -u FILE True if FILE has suid bit set.
|
| 1076 | -w FILE True if FILE is writable.
|
| 1077 | -x FILE True if FILE is executable.
|
| 1078 | FILE1 -nt FILE2 True if FILE1 is newer than FILE2 (mtime).
|
| 1079 | FILE1 -ot FILE2 True if FILE1 is older than FILE2 (mtime).
|
| 1080 | FILE1 -ef FILE2 True if FILE1 is a hard link to FILE2.
|
| 1081 | <!-- -N FILE True if FILE was modified since last read (mtime newer than atime).-->
|
| 1082 |
|
| 1083 | Arithmetic expressions coerce arguments to integers, then compare:
|
| 1084 |
|
| 1085 | INT1 -eq INT2 True if they're equal.
|
| 1086 | INT1 -ne INT2 True if they're not equal.
|
| 1087 | INT1 -lt INT2 True if INT1 is less than INT2.
|
| 1088 | INT1 -le INT2 True if INT1 is less or equal than INT2.
|
| 1089 | INT1 -gt INT2 True if INT1 is greater than INT2.
|
| 1090 | INT1 -ge INT2 True if INT1 is greater or equal than INT2.
|
| 1091 |
|
| 1092 | Other expressions:
|
| 1093 |
|
| 1094 | -o OPTION True if the shell option OPTION is set.
|
| 1095 | -v VAR True if the variable VAR is set.
|
| 1096 |
|
| 1097 | The test builtin also supports POSIX conditionals like -a, -o, !, and ( ), but
|
| 1098 | these are discouraged.
|
| 1099 |
|
| 1100 | <!-- -R VAR True if the variable VAR has been set and is a nameref variable. -->
|
| 1101 |
|
| 1102 | Oils supports these long flags:
|
| 1103 |
|
| 1104 | --dir same as -d
|
| 1105 | --exists same as -e
|
| 1106 | --file same as -f
|
| 1107 | --symlink same as -L
|
| 1108 |
|
| 1109 | ### getopts
|
| 1110 |
|
| 1111 | getopts SPEC VAR ARG*
|
| 1112 |
|
| 1113 | A single iteration of flag parsing. The SPEC is a sequence of flag characters,
|
| 1114 | with a trailing `:` to indicate that the flag takes an argument:
|
| 1115 |
|
| 1116 | ab # accept -a and -b
|
| 1117 | xy:z # accept -x, -y arg, and -z
|
| 1118 |
|
| 1119 | The input is `"$@"` by default, unless ARGs are passed.
|
| 1120 |
|
| 1121 | On each iteration, the flag character is stored in VAR. If the flag has an
|
| 1122 | argument, it's stored in `$OPTARG`. When an error occurs, VAR is set to `?`
|
| 1123 | and `$OPTARG` is unset.
|
| 1124 |
|
| 1125 | Returns 0 if a flag is parsed, or 1 on end of input or another error.
|
| 1126 |
|
| 1127 | Example:
|
| 1128 |
|
| 1129 | while getopts "ab:" flag; do
|
| 1130 | case $flag in
|
| 1131 | a) flag_a=1 ;;
|
| 1132 | b) flag_b=$OPTARG" ;;
|
| 1133 | '?') echo 'Invalid Syntax'; break ;;
|
| 1134 | esac
|
| 1135 | done
|
| 1136 |
|
| 1137 | Notes:
|
| 1138 | - `$OPTIND` is initialized to 1 every time a shell starts, and is used to
|
| 1139 | maintain state between invocations of `getopts`.
|
| 1140 | - The characters `:` and `?` can't be flags.
|
| 1141 |
|
| 1142 | ### kill
|
| 1143 |
|
| 1144 | Unimplemented.
|
| 1145 |
|
| 1146 | <!-- Note: 'kill' accepts job control syntax -->
|
| 1147 |
|
| 1148 | ## Introspection
|
| 1149 |
|
| 1150 | <h3 id="help" class="osh-topic ysh-topic" oils-embed="1">
|
| 1151 | help
|
| 1152 | </h3>
|
| 1153 |
|
| 1154 | <!-- pre-formatted for help builtin -->
|
| 1155 |
|
| 1156 | ```
|
| 1157 | Usage: help TOPIC?
|
| 1158 |
|
| 1159 | Examples:
|
| 1160 |
|
| 1161 | help # this help
|
| 1162 | help echo # help on the 'echo' builtin
|
| 1163 | help command-sub # help on command sub $(date)
|
| 1164 |
|
| 1165 | help oils-usage # identical to oils-for-unix --help
|
| 1166 | help osh-usage # osh --help
|
| 1167 | help ysh-usage # ysh --help
|
| 1168 | ```
|
| 1169 |
|
| 1170 | ### hash
|
| 1171 |
|
| 1172 | hash
|
| 1173 |
|
| 1174 | Display information about remembered commands.
|
| 1175 |
|
| 1176 | hash FLAG* CMD+
|
| 1177 |
|
| 1178 | Determine the locations of commands using `$PATH`, and remember them.
|
| 1179 |
|
| 1180 | Flag:
|
| 1181 |
|
| 1182 | -r Discard all remembered locations.
|
| 1183 | <!-- -d Discard the remembered location of each NAME.
|
| 1184 | -l Display output in a format reusable as input.
|
| 1185 | -p PATH Inhibit path search, PATH is used as location for NAME.
|
| 1186 | -t Print the full path of one or more NAME.-->
|
| 1187 |
|
| 1188 | ### cmd/type
|
| 1189 |
|
| 1190 | type FLAG* NAME+
|
| 1191 |
|
| 1192 | Print the type of each NAME, if it were the first word of a command. Is it a
|
| 1193 | shell keyword, builtin command, shell function, alias, or executable file on
|
| 1194 | $PATH?
|
| 1195 |
|
| 1196 | Flags:
|
| 1197 |
|
| 1198 | -a Show all possible candidates, not just the first one
|
| 1199 | -f Don't search for shell functions
|
| 1200 | -P Only search for executable files
|
| 1201 | -t Print a single word: alias, builtin, file, function, or keyword
|
| 1202 |
|
| 1203 | Similar names: [type][]
|
| 1204 |
|
| 1205 | [type]: chap-index.html#type
|
| 1206 |
|
| 1207 | <!-- TODO:
|
| 1208 | - procs are counted as shell functions, should be their own thing
|
| 1209 | - Hay nodes ('hay define x') also live in the first word namespace, and should
|
| 1210 | be recognized
|
| 1211 | -->
|
| 1212 |
|
| 1213 | Modeled after the [bash `type`
|
| 1214 | builtin](https://www.gnu.org/software/bash/manual/bash.html#index-type).
|
| 1215 |
|
| 1216 | ## Word Lookup
|
| 1217 |
|
| 1218 | ### command
|
| 1219 |
|
| 1220 | command FLAG* CMD ARG*
|
| 1221 |
|
| 1222 | Look up CMD as a shell builtin or executable file, and execute it with the
|
| 1223 | given ARGs. That is, the lookup ignores shell functions named CMD.
|
| 1224 |
|
| 1225 | Flags:
|
| 1226 |
|
| 1227 | -v Instead of executing CMD, print a description of it.
|
| 1228 | Similar to the 'type' builtin.
|
| 1229 | <!-- -p Use a default value for PATH that is guaranteed to find all of the
|
| 1230 | standard utilities.
|
| 1231 | -V Print a more verbose description of CMD.-->
|
| 1232 |
|
| 1233 | ### builtin
|
| 1234 |
|
| 1235 | builtin CMD ARG*
|
| 1236 |
|
| 1237 | Look up CMD as a shell builtin, and execute it with the given ARGs. That is,
|
| 1238 | the lookup ignores shell functions and executables named CMD.
|
| 1239 |
|
| 1240 | ## Interactive
|
| 1241 |
|
| 1242 | ### alias
|
| 1243 |
|
| 1244 | alias NAME=CODE
|
| 1245 |
|
| 1246 | Make NAME a shortcut for executing CODE, e.g. `alias hi='echo hello'`.
|
| 1247 |
|
| 1248 | alias NAME
|
| 1249 |
|
| 1250 | Show the value of this alias.
|
| 1251 |
|
| 1252 | alias
|
| 1253 |
|
| 1254 | Show a list of all aliases.
|
| 1255 |
|
| 1256 | Tips:
|
| 1257 |
|
| 1258 | Prefer shell functions like:
|
| 1259 |
|
| 1260 | ls() {
|
| 1261 | command ls --color "$@"
|
| 1262 | }
|
| 1263 |
|
| 1264 | to aliases like:
|
| 1265 |
|
| 1266 | alias ls='ls --color'
|
| 1267 |
|
| 1268 | Functions are less likely to cause parsing problems.
|
| 1269 |
|
| 1270 | - Quoting like `\ls` or `'ls'` disables alias expansion
|
| 1271 | - To remove an existing alias, use [unalias](chap-builtin-cmd.html#unalias).
|
| 1272 |
|
| 1273 | ### unalias
|
| 1274 |
|
| 1275 | unalias NAME
|
| 1276 |
|
| 1277 | Remove the alias NAME.
|
| 1278 |
|
| 1279 | <!--Flag:
|
| 1280 |
|
| 1281 | -a Removes all existing aliases.-->
|
| 1282 |
|
| 1283 | ### history
|
| 1284 |
|
| 1285 | history FLAG*
|
| 1286 |
|
| 1287 | Display and manipulate the shell's history entries.
|
| 1288 |
|
| 1289 | history NUM
|
| 1290 |
|
| 1291 | Show the last NUM history entries.
|
| 1292 |
|
| 1293 | Flags:
|
| 1294 |
|
| 1295 | -c Clears the history.
|
| 1296 | -d POS Deletes the history entry at position POS.
|
| 1297 | <!-- -a
|
| 1298 | -n
|
| 1299 | -r
|
| 1300 | -w
|
| 1301 | -p
|
| 1302 | -s -->
|
| 1303 |
|
| 1304 |
|
| 1305 | ## Unsupported
|
| 1306 |
|
| 1307 | ### enable
|
| 1308 |
|
| 1309 | Bash has this, but OSH won't implement it.
|
| 1310 |
|
| 1311 |
|
| 1312 | ## Args Parser
|
| 1313 |
|
| 1314 | YSH includes a command-line argument parsing utility called `parseArgs`. This
|
| 1315 | is intended to be used for command-line interfaces to YSH programs.
|
| 1316 |
|
| 1317 | To use it, first import `args.ysh`:
|
| 1318 |
|
| 1319 | source --builtin args.ysh
|
| 1320 |
|
| 1321 | Then, create an argument parser **spec**ification:
|
| 1322 |
|
| 1323 | parser (&spec) {
|
| 1324 | flag -v --verbose (help="Verbosely") # default is Bool, false
|
| 1325 |
|
| 1326 | flag -P --max-procs ('int', default=-1, help='''
|
| 1327 | Run at most P processes at a time
|
| 1328 | ''')
|
| 1329 |
|
| 1330 | flag -i --invert ('bool', default=true, help='''
|
| 1331 | Long multiline
|
| 1332 | Description
|
| 1333 | ''')
|
| 1334 |
|
| 1335 | arg src (help='Source')
|
| 1336 | arg dest (help='Dest')
|
| 1337 |
|
| 1338 | rest files
|
| 1339 | }
|
| 1340 |
|
| 1341 | Finally, parse `ARGV` (or any other array of strings) with:
|
| 1342 |
|
| 1343 | var args = parseArgs(spec, ARGV)
|
| 1344 |
|
| 1345 | The returned `args` is a `Dict` containing key-value pairs with the parsed
|
| 1346 | values (or defaults) for each flag and argument. For example, given
|
| 1347 | `ARGV = :| mysrc -P 12 mydest a b c |`, `args` would be:
|
| 1348 |
|
| 1349 | {
|
| 1350 | "verbose": false,
|
| 1351 | "max-procs": 12,
|
| 1352 | "invert": true,
|
| 1353 | "src": "mysrc",
|
| 1354 | "dest": "mydest",
|
| 1355 | "files": ["a", "b", "c"]
|
| 1356 | }
|
| 1357 |
|
| 1358 | ### parser
|
| 1359 |
|
| 1360 | `parseArgs()` requires a parser specification to indicate how to parse the
|
| 1361 | `ARGV` array. This specification should be constructed using the `parser` proc.
|
| 1362 |
|
| 1363 | parser (&spec) {
|
| 1364 | flag -f --my-flag
|
| 1365 | arg myarg
|
| 1366 | rest otherArgs
|
| 1367 | }
|
| 1368 |
|
| 1369 | In the above example, `parser` takes in a place `&spec`, which will store the
|
| 1370 | resulting specification and a block which is evaluated to build that
|
| 1371 | specification.
|
| 1372 |
|
| 1373 | Inside of a `parser` block, you should call the following procs:
|
| 1374 |
|
| 1375 | - `flag` to add `--flag` options
|
| 1376 | - `arg` to add positional arguments
|
| 1377 | - `rest` to capture remaining positional arguments into a list
|
| 1378 |
|
| 1379 | `parser` will validate the parser specification for errors such as duplicate
|
| 1380 | flag or argument names.
|
| 1381 |
|
| 1382 | parser (&spec) {
|
| 1383 | flag -n --name
|
| 1384 | flag -n --name # Duplicate!
|
| 1385 | }
|
| 1386 |
|
| 1387 | # => raises "Duplicate flag/arg name 'name' in spec" (status = 3)
|
| 1388 |
|
| 1389 | ### flag
|
| 1390 |
|
| 1391 | `flag` should be called within a `parser` block.
|
| 1392 |
|
| 1393 | parser (&spec) {
|
| 1394 | flag -v --verbose
|
| 1395 | }
|
| 1396 |
|
| 1397 | The above example declares a flag "--verbose" and a short alias "-v".
|
| 1398 | `parseArgs()` will then store a boolean value under `args.verbose`:
|
| 1399 | - `true` if the flag was passed at least once
|
| 1400 | - `false` otherwise
|
| 1401 |
|
| 1402 | Flags can also accept values. For example, if you wanted to accept an integer count:
|
| 1403 |
|
| 1404 | parser (&spec) {
|
| 1405 | flag -N --count ('int')
|
| 1406 | }
|
| 1407 |
|
| 1408 | Calling `parseArgs` with `ARGV = :| -n 5 |` or `ARGV = :| --count 5 |` will
|
| 1409 | store the integer `5` under `args.count`. If the user passes in a non-integer
|
| 1410 | value like `ARGV = :| --count abc |`, `parseArgs` will raise an error.
|
| 1411 |
|
| 1412 | Default values for an argument can be set with the `default` named argument.
|
| 1413 |
|
| 1414 | parser (&spec) {
|
| 1415 | flag -N --count ('int', default=2)
|
| 1416 |
|
| 1417 | # Boolean flags can be given default values too
|
| 1418 | flag -O --optimize ('bool', default=true)
|
| 1419 | }
|
| 1420 |
|
| 1421 | var args = parseArgs(spec, :| -n 3 |)
|
| 1422 | # => args.count = 2
|
| 1423 | # => args.optimize = true
|
| 1424 |
|
| 1425 | Each name passed to `flag` must be unique to that specific `parser`. Calling
|
| 1426 | `flag` with the same name twice will raise an error inside of `parser`.
|
| 1427 |
|
| 1428 | <!-- TODO: how can we explicitly pass false to a boolean flag? -->
|
| 1429 | <!-- TODO: how about --no-XXXX variants of flags? -->
|
| 1430 |
|
| 1431 | ### arg
|
| 1432 |
|
| 1433 | `arg` should be called within a `parser` block.
|
| 1434 |
|
| 1435 | parser (&spec) {
|
| 1436 | arg query
|
| 1437 | arg path
|
| 1438 | }
|
| 1439 |
|
| 1440 | The above example declares two positional arguments called "query" and "path".
|
| 1441 | `parseArgs()` will then store strings under `args.query` and `args.path`. Order
|
| 1442 | matters, so the first positional argument will be stored to `query` and the
|
| 1443 | second to `path`. If not enough positional arguments are passed, then
|
| 1444 | `parseArgs` will raise an error.
|
| 1445 |
|
| 1446 | Similar to `flag`, each `arg` name must be unique. Calling `arg` with the same
|
| 1447 | name twice will cause `parser` to raise an error.
|
| 1448 |
|
| 1449 | ### rest
|
| 1450 |
|
| 1451 | `rest` should be called within a `parser` block.
|
| 1452 |
|
| 1453 | parser (&spec) {
|
| 1454 | arg query
|
| 1455 | rest files
|
| 1456 | }
|
| 1457 |
|
| 1458 | Capture zero or more positional arguments not already captured by `arg`. So,
|
| 1459 | for `ARGV = :| hello file.txt message.txt README.md |`, we would have
|
| 1460 | `args.query = "file.txt"` and `args.files = ["file.txt", "message.txt",
|
| 1461 | "README.md"]`.
|
| 1462 |
|
| 1463 | Without rest, passing extraneous arguments will raise an error in
|
| 1464 | `parseArgs()`.
|
| 1465 |
|
| 1466 | `rest` can only be called _once_ within a `parser`. Calling it multiple times
|
| 1467 | will raise an error in `parser`.
|
| 1468 |
|
| 1469 | ### parseArgs()
|
| 1470 |
|
| 1471 | Given a parser specification `spec` produced by `parser`, parse a list of
|
| 1472 | strings (usually `ARGV`.)
|
| 1473 |
|
| 1474 | var args = parseArgs(spec, ARGV)
|
| 1475 |
|
| 1476 | The returned `args` is a dictionary mapping the names of each `arg`, `flag` and
|
| 1477 | `rest` to their captured values. (See the example at the [start of this
|
| 1478 | topic](#Args-Parser).)
|
| 1479 |
|
| 1480 | `parseArgs` will raise an error if the `ARGV` is invalid per the parser
|
| 1481 | specification. For example, if it's missing a required positional argument:
|
| 1482 |
|
| 1483 | parser (&spec) {
|
| 1484 | arg path
|
| 1485 | }
|
| 1486 |
|
| 1487 | var args = parseArgs(spec, [])
|
| 1488 | # => raises an error about the missing 'path' (status = 2)
|
| 1489 |
|
| 1490 | <!--
|
| 1491 | TODO: Document chaining parsers / sub-commands
|
| 1492 | - Either will allow parser nesting
|
| 1493 | - Or can use `rest rest` and `parseArgs` again on `rest`
|
| 1494 | TODO: Document the help named argument. Punting while we do not generate help messages
|
| 1495 | -->
|