| 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 | ### error
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| 63 |
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| 64 | The `error` builtin interrupts shell execution.
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| 65 |
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| 66 | If there's a surrounding `try` block, the `_error` register is set, and
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| 67 | execution proceeds after the block.
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| 68 |
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| 69 | Otherwise, the shell exits with a non-zero status.
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| 70 |
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| 71 | Examples:
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| 72 |
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| 73 | error 'Missing /tmp' # program fails with status 10
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| 74 |
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| 75 | try {
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| 76 | error 'Another problem'
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| 77 | }
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| 78 | echo $[error.code] # => 10
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| 79 |
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| 80 | Override the default error code of `10` with a named argument:
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| 81 |
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| 82 | error 'Missing /tmp' (code=99) # program fails with status 99
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| 83 |
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| 84 | Named arguments add arbitrary properties to the resulting `_error` register:
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| 85 |
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| 86 | error 'Oops' (path='foo.json')
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| 87 |
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| 88 | See [YSH Error Handling](../ysh-error-handling.html) for more examples.
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| 89 |
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| 90 | ### failed
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| 91 |
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| 92 | A shortcut for `(_error.code !== 0)`:
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| 93 |
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| 94 | try {
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| 95 | ls /tmp
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| 96 | }
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| 97 | if failed {
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| 98 | echo 'ls failed'
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| 99 | }
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| 100 |
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| 101 | It saves you 7 punctuation characters: `( _ . !== )`
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| 102 |
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| 103 | See [YSH Error Handling](../ysh-error-handling.html) for more examples.
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| 104 |
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| 105 | ### try
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| 106 |
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| 107 | Run a block of code, stopping at the first error. (This is implemented with
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| 108 | `shopt --set errexit`)
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| 109 |
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| 110 | `try` sets the `_error` register to a dict, and always returns 0.
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| 111 |
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| 112 | try {
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| 113 | ls /nonexistent
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| 114 | }
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| 115 | if (_error.code !== 0) {
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| 116 | echo 'ls failed'
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| 117 | }
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| 118 |
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| 119 | Handle expression errors:
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| 120 |
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| 121 | try {
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| 122 | var x = 42 / 0
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| 123 | }
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| 124 |
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| 125 | And errors from compound commands:
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| 126 |
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| 127 | try {
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| 128 | ls | wc -l
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| 129 | diff <(sort left.txt) <(sort right.txt)
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| 130 | }
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| 131 |
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| 132 | The case statement can be useful:
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| 133 |
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| 134 | try {
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| 135 | grep PATTERN FILE.txt
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| 136 | }
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| 137 | case (_error.code) {
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| 138 | (0) { echo 'found' }
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| 139 | (1) { echo 'not found' }
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| 140 | (else) { echo "grep returned status $[_error.code]" }
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| 141 | }
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| 142 |
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| 143 | See [YSH Error Handling](../ysh-error-handling.html) for more examples.
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| 144 |
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| 145 | ### boolstatus
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| 146 |
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| 147 | Runs a command, and requires the exit code to be 0 or 1.
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| 148 |
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| 149 | if boolstatus egrep '[0-9]+' myfile { # e.g. aborts on status 2
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| 150 | echo 'found' # status 0 means found
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| 151 | } else {
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| 152 | echo 'not found' # status 1 means not found
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| 153 | }
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| 154 |
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| 155 | It's meant for external commands that "return" more than 2 values, like true /
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| 156 | false / fail, rather than pass / fail.
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| 157 |
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| 158 | ## Shell State
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| 159 |
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| 160 | ### ysh-cd
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| 161 |
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| 162 | It takes a block:
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| 163 |
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| 164 | cd / {
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| 165 | echo $PWD
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| 166 | }
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| 167 |
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| 168 | ### ysh-shopt
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| 169 |
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| 170 | It takes a block:
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| 171 |
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| 172 | shopt --unset errexit {
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| 173 | false
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| 174 | echo 'ok'
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| 175 | }
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| 176 |
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| 177 | ### shvar
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| 178 |
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| 179 | Execute a block with a global variable set.
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| 180 |
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| 181 | shvar IFS=/ {
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| 182 | echo "ifs is $IFS"
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| 183 | }
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| 184 | echo "ifs restored to $IFS"
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| 185 |
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| 186 | ### ctx
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| 187 |
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| 188 | Execute a block with a shared "context" that can be updated using the `ctx`
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| 189 | built-in.
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| 190 |
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| 191 | var mydict = {}
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| 192 | ctx push (mydict) {
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| 193 | # = mydict => {}
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| 194 | ctx set (mykey='myval')
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| 195 | }
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| 196 | # = mydict => { mykey: 'myval' }
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| 197 |
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| 198 | The context can be modified with `ctx set (key=val)`, which updates or inserts
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| 199 | the value at the given key.
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| 200 |
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| 201 | The context can also be updated with `ctx emit field (value)`.
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| 202 |
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| 203 | ctx push (mydict) {
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| 204 | # = mydict => {}
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| 205 | ctx emit mylist (0)
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| 206 | # = mydict => { mylist: [0] }
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| 207 | ctx emit mylist (1)
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| 208 | }
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| 209 | # = mydict => { mylist: [0, 1] }
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| 210 |
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| 211 | Contexts can be nested, resulting in a stack of contexts.
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| 212 |
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| 213 | ctx push (mydict1) {
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| 214 | ctx set (dict=1)
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| 215 | ctx push (mydict2) {
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| 216 | ctx set (dict=2)
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| 217 | }
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| 218 | }
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| 219 | # = mydict1 => { dict: 1 }
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| 220 | # = mydict2 => { dict: 2 }
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| 221 |
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| 222 | `ctx` is useful for creating DSLs, such as a mini-parseArgs.
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| 223 |
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| 224 | proc parser (; place ; ; block_def) {
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| 225 | var p = {}
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| 226 | ctx push (p, block_def)
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| 227 | call place->setValue(p)
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| 228 | }
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| 229 |
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| 230 | proc flag (short_name, long_name; type; help) {
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| 231 | ctx emit flag ({short_name, long_name, type, help})
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| 232 | }
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| 233 |
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| 234 | proc arg (name) {
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| 235 | ctx emit arg ({name})
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| 236 | }
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| 237 |
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| 238 | parser (&spec) {
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| 239 | flag -t --tsv (Bool, help='Output as TSV')
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| 240 | flag -r --recursive (Bool, help='Recurse into the given directory')
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| 241 | flag -N --count (Int, help='Process no more than N files')
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| 242 | arg path
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| 243 | }
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| 244 |
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| 245 | ### push-registers
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| 246 |
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| 247 | Save global registers like $? on a stack. It's useful for preventing plugins
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| 248 | from interfering with user code. Example:
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| 249 |
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| 250 | status_42 # returns 42 and sets $?
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| 251 | push-registers { # push a new frame
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| 252 | status_43 # top of stack changed here
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| 253 | echo done
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| 254 | } # stack popped
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| 255 | echo $? # 42, read from new top-of-stack
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| 256 |
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| 257 | Current list of registers:
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| 258 |
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| 259 | Regex data underlying BASH_REMATCH, _group(), _start(), _end()
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| 260 | $?
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| 261 | _error # set by the try builtin
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| 262 | PIPESTATUS # aka _pipeline_status
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| 263 | _process_sub_status
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| 264 |
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| 265 |
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| 266 | ## Modules
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| 267 |
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| 268 | ### runproc
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| 269 |
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| 270 | Runs a named proc with the given arguments. It's often useful as the only top
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| 271 | level statement in a "task file":
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| 272 |
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| 273 | proc p {
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| 274 | echo hi
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| 275 | }
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| 276 | runproc @ARGV
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| 277 |
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| 278 | Like 'builtin' and 'command', it affects the lookup of the first word.
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| 279 |
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| 280 | ### module
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| 281 |
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| 282 | Registers a name in the global module dict. Returns 0 if it doesn't exist, or
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| 283 | 1 if it does.
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| 284 |
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| 285 | Use it like this in executable files:
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| 286 |
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| 287 | module main || return 0
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| 288 |
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| 289 | And like this in libraries:
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| 290 |
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| 291 | module myfile.ysh || return 0
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| 292 |
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| 293 | ### is-main
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| 294 |
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| 295 | The `is-main` builtin returns 1 (false) if the current file was executed with
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| 296 | the `source` builtin.
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| 297 |
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| 298 | In the "main" file, including `-c` or `stdin` input, it returns 0 (true).
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| 299 |
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| 300 | Use it like this:
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| 301 |
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| 302 | if is-main {
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| 303 | runproc @ARGV
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| 304 | }
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| 305 |
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| 306 | ### use
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| 307 |
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| 308 | TODO
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| 309 |
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| 310 | Reuse code from other files, respecting namespaces.
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| 311 |
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| 312 | use lib/foo.ysh # relative import, i.ie implicit $_this_dir?
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| 313 | # makes name 'foo' available
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| 314 |
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| 315 | Bind a specific name:
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| 316 |
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| 317 | use lib/foo.ysh (&myvar) # makes 'myvar' available
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| 318 |
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| 319 | Bind multiple names:
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| 320 |
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| 321 | use lib/foo.ysh (&myvar) {
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| 322 | var log, die
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| 323 | }
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| 324 |
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| 325 | Maybe:
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| 326 |
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| 327 | use lib/foo.ysh (&myvar) {
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| 328 | var mylog = myvar.log
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| 329 | }
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| 330 |
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| 331 | Also a declaration
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| 332 |
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| 333 | use --extern grep sed
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| 334 |
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| 335 | ## I/O
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| 336 |
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| 337 | ### ysh-read
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| 338 |
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| 339 | YSH adds long flags to shell's `read`:
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| 340 |
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| 341 | read --all # whole file including trailing \n, fills $_reply
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| 342 | read --all (&x) # fills $x
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| 343 |
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| 344 | read --num-bytes 3 # read N bytes, fills _reply
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| 345 | read --num-bytes 3 (&x) # fills $x
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| 346 |
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| 347 | read --raw-line # unbuffered read of line, omitting trailing \n
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| 348 | read --raw-line (&x) # fills $x
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| 349 |
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| 350 | read --raw-line --with-eol # include the trailing \n
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| 351 |
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| 352 | And a convenience:
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| 353 |
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| 354 | read -0 # read until NUL, synonym for read -r -d ''
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| 355 |
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| 356 | You may want to use `fromJson8()` or `fromJson()` after reading a line.
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| 357 |
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| 358 | <!--
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| 359 |
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| 360 | TODO:
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| 361 |
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| 362 | - read --netstr
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| 363 | - fromJ8Line() is different than from Json8! It's like @()
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| 364 |
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| 365 | -->
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| 366 |
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| 367 | <!--
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| 368 |
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| 369 | Problem with read --json -- there's also https://jsonlines.org, which allows
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| 370 |
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| 371 | {"my": "line"}
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| 372 |
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| 373 | That can be done with
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| 374 |
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| 375 | while read --line {
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| 376 | var record = fromJson(_reply)
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| 377 | }
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| 378 |
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| 379 | This is distinct from:
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| 380 |
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| 381 | while read --line --j8 {
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| 382 | echo $_reply
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| 383 | }
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| 384 |
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| 385 | This allows unquoted. Maybe it should be read --j8-line
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| 386 |
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| 387 | What about write? These would be the same:
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| 388 |
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| 389 | write --json -- $s
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| 390 | write --j8 -- $s
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| 391 |
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| 392 | write -- $[toJson(s)]
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| 393 | write -- $[toJson8(s)]
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| 394 |
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| 395 | write --json -- @strs
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| 396 | write --j8 -- @strs
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| 397 |
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| 398 | write -- @[toJson(s) for s in strs]
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| 399 | write -- @[toJson8(s) for s in strs]
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| 400 |
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| 401 | It's an argument for getting rid --json and --j8? I already implemented them,
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| 402 | but it makes the API smaller.
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| 403 |
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| 404 | I guess the main thing would be to AVOID quoting sometimes?
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| 405 |
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| 406 | $ write --j8 -- unquoted
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| 407 | unquoted
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| 408 |
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| 409 | $ write --j8 -- $'\'' '"'
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| 410 | "'"
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| 411 | "\""
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| 412 |
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| 413 | I think this could be the shell style?
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| 414 |
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| 415 | $ write --shell-str -- foo bar baz
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| 416 |
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| 417 | Or it could be
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| 418 |
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| 419 | $ write -- @[toShellString(s) for s in strs]
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| 420 |
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| 421 | I want this to be "J8 Lines", but it can be done in pure YSH. It's not built
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| 422 | into the interpreter.
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| 423 |
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| 424 | foo/bar
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| 425 | "hi"
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| 426 | b'hi'
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| 427 | u'hi'
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| 428 |
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| 429 | But what about
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| 430 |
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| 431 | Fool's Gold
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| 432 | a'hi' # This feels like an error?
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| 433 | a"hi" # what about this?
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| 434 |
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| 435 | Technically we CAN read those as literal strings
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| 436 | -->
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| 437 |
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| 438 | ### ysh-echo
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| 439 |
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| 440 | Print arguments to stdout, separated by a space.
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| 441 |
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| 442 | ysh$ echo hi there
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| 443 | hi there
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| 444 |
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| 445 | The [simple_echo][] option means that flags aren't accepted, and `--` is not
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| 446 | accepted.
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| 447 |
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| 448 | ysh$ echo -n
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| 449 | -n
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| 450 |
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| 451 | See the [YSH FAQ][echo-en] for details.
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| 452 |
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| 453 | [simple_echo]: chap-option.html#ysh:all
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| 454 | [echo-en]: ../ysh-faq.html#how-do-i-write-the-equivalent-of-echo-e-or-echo-n
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| 455 |
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| 456 | ### write
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| 457 |
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| 458 | write fixes problems with shell's `echo` builtin.
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| 459 |
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| 460 | The default separator is a newline, and the default terminator is a
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| 461 | newline.
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| 462 |
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| 463 | Examples:
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| 464 |
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| 465 | write -- ale bean # write two lines
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| 466 |
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| 467 | write -n -- ale bean # synonym for --end '', like echo -n
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| 468 | write --sep '' --end '' -- a b # write 2 bytes
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| 469 | write --sep $'\t' --end $'\n' -- a b # TSV line
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| 470 |
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| 471 | You may want to use `toJson8()` or `toJson()` before writing:
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| 472 |
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| 473 | write -- $[toJson8(mystr)]
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| 474 | write -- $[toJson(mystr)]
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| 475 |
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| 476 |
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| 477 | <!--
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| 478 | write --json -- ale bean # JSON encode, guarantees two lines
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| 479 | write --j8 -- ale bean # J8 encode, guarantees two lines
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| 480 | -->
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| 481 |
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| 482 |
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| 483 | ### fork
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| 484 |
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| 485 | Run a command, but don't wait for it to finish.
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| 486 |
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| 487 | fork { sleep 1 }
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| 488 | wait -n
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| 489 |
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| 490 | In YSH, use `fork` rather than shell's `&` ([ampersand][]).
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| 491 |
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| 492 | [ampersand]: chap-cmd-lang.html#ampersand
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| 493 |
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| 494 | ### forkwait
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| 495 |
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| 496 | The preferred alternative to shell's `()`. Prefer `cd` with a block if possible.
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| 497 |
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| 498 | forkwait {
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| 499 | not_mutated=zzz
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| 500 | }
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| 501 | echo $not_mutated
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| 502 |
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| 503 | ### fopen
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| 504 |
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| 505 | Runs a block passed to it. It's designed so redirects have a **prefix**
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| 506 | syntax:
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| 507 |
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| 508 | fopen >out.txt {
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| 509 | echo 1
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| 510 | echo 2
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| 511 | }
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| 512 |
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| 513 | Rather than shell style:
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| 514 |
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| 515 | { echo 1
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| 516 | echo 2
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| 517 | } >out.txt
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| 518 |
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| 519 | When a block is long, the former is more readable.
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| 520 |
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| 521 | ## Hay Config
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| 522 |
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| 523 | ### hay
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| 524 |
|
| 525 | ### haynode
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| 526 |
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| 527 |
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| 528 | ## Data Formats
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| 529 |
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| 530 | ### json
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| 531 |
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| 532 | Write JSON:
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| 533 |
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| 534 | var d = {name: 'bob', age: 42}
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| 535 | json write (d) # default indentation of 2
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| 536 | json write (d, space=0) # no indentation
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| 537 |
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| 538 | Read JSON:
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| 539 |
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| 540 | echo hi | json read # fills $_reply by default
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| 541 |
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| 542 | Or use an explicit place:
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| 543 |
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| 544 | var x = ''
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| 545 | json read (&x) < myfile.txt
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| 546 |
|
| 547 | Related: [err-json-encode][] and [err-json-decode][]
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| 548 |
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| 549 | [err-json-encode]: chap-errors.html#err-json-encode
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| 550 | [err-json-decode]: chap-errors.html#err-json-decode
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| 551 |
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| 552 | ### json8
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| 553 |
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| 554 | Like `json`, but on the encoding side:
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| 555 |
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| 556 | - Falls back to `b'\yff'` instead of lossy Unicode replacement char
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| 557 |
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| 558 | On decoding side:
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| 559 |
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| 560 | - Understands `b'' u''` strings
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| 561 |
|
| 562 | Related: [err-json8-encode]() and [err-json8-decode]()
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| 563 |
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| 564 | [err-json8-encode]: chap-errors.html#err-json8-encode
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| 565 | [err-json8-decode]: chap-errors.html#err-json8-decode
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| 566 |
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| 567 | ## Testing
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| 568 |
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| 569 | TODO: describe
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| 570 |
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| 571 | ## External Lang
|
| 572 |
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| 573 | TODO: when
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| 574 |
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| 575 |
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| 576 | ## I/O
|
| 577 |
|
| 578 | These builtins take input and output. They're often used with redirects.
|
| 579 |
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| 580 | ### read
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| 581 |
|
| 582 | read FLAG* VAR*
|
| 583 |
|
| 584 | Read a line from stdin, split it into tokens with the `$IFS` algorithm,
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| 585 | and assign the tokens to the given variables. When no VARs are given,
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| 586 | assign to `$REPLY`.
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| 587 |
|
| 588 | Note: When writing ySH, prefer the extensions documented in
|
| 589 | [ysh-read](#ysh-read). The `read` builtin is confusing because `-r` needs to
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| 590 | be explicitly enabled.
|
| 591 |
|
| 592 | Flags:
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| 593 |
|
| 594 | -a ARRAY assign the tokens to elements of this array
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| 595 | -d CHAR use DELIM as delimiter, instead of newline
|
| 596 | -n NUM read up to NUM characters, respecting delimiters
|
| 597 | -p STR print the string PROMPT before reading input
|
| 598 | -r raw mode: don't let backslashes escape characters
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| 599 | -s silent: do not echo input coming from a terminal
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| 600 | -t NUM time out and fail after TIME seconds
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| 601 | -t 0 returns whether any input is available
|
| 602 | -u FD read from file descriptor FD instead of 0 (stdin)
|
| 603 |
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| 604 | <!-- -N NUM read up to NUM characters, ignoring delimiters -->
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| 605 | <!-- -e use readline to obtain the line
|
| 606 | -i STR use STR as the initial text for readline -->
|
| 607 |
|
| 608 | ### echo
|
| 609 |
|
| 610 | echo FLAG* ARG*
|
| 611 |
|
| 612 | Prints ARGs to stdout, separated by a space, and terminated by a newline.
|
| 613 |
|
| 614 | Flags:
|
| 615 |
|
| 616 | -e enable interpretation of backslash escapes
|
| 617 | -n omit the trailing newline
|
| 618 | <!-- -E -->
|
| 619 |
|
| 620 | See [char-escapes](chap-mini-lang.html#char-escapes).
|
| 621 |
|
| 622 | ### printf
|
| 623 |
|
| 624 | printf FLAG* FMT ARG*
|
| 625 |
|
| 626 | Formats values and prints them. The FMT string contain three types of objects:
|
| 627 |
|
| 628 | 1. Literal Characters
|
| 629 | 2. Character escapes like `\t`. See [char-escapes](chap-mini-lang.html#char-escapes).
|
| 630 | 3. Percent codes like `%s` that specify how to format each each ARG.
|
| 631 |
|
| 632 | If not enough ARGS are passed, the empty string is used. If too many are
|
| 633 | passed, the FMT string will be "recycled".
|
| 634 |
|
| 635 | Flags:
|
| 636 |
|
| 637 | -v VAR Write output in variable VAR instead of standard output.
|
| 638 |
|
| 639 | Format specifiers:
|
| 640 |
|
| 641 | %% Prints a single "%".
|
| 642 | %b Interprets backslash escapes while printing.
|
| 643 | %q Prints the argument escaping the characters needed to make it reusable
|
| 644 | as shell input.
|
| 645 | %d Print as signed decimal number.
|
| 646 | %i Same as %d.
|
| 647 | %o Print as unsigned octal number.
|
| 648 | %u Print as unsigned decimal number.
|
| 649 | %x Print as unsigned hexadecimal number with lower-case hex-digits (a-f).
|
| 650 | %X Same as %x, but with upper-case hex-digits (A-F).
|
| 651 | %f Print as floating point number.
|
| 652 | %e Print as a double number, in "±e" format (lower-case e).
|
| 653 | %E Same as %e, but with an upper-case E.
|
| 654 | %g Interprets the argument as double, but prints it like %f or %e.
|
| 655 | %G Same as %g, but print it like %E.
|
| 656 | %c Print as a single char, only the first character is printed.
|
| 657 | %s Print as string
|
| 658 | %n The number of characters printed so far is stored in the variable named
|
| 659 | in the argument.
|
| 660 | %a Interprets the argument as double, and prints it like a C99 hexadecimal
|
| 661 | floating-point literal.
|
| 662 | %A Same as %a, but print it like %E.
|
| 663 | %(FORMAT)T Prints date and time, according to FORMAT as a format string
|
| 664 | for strftime(3). The argument is the number of seconds since
|
| 665 | epoch. It can also be -1 (current time, also the default value
|
| 666 | if there is no argument) or -2 (shell startup time).
|
| 667 |
|
| 668 | ### readarray
|
| 669 |
|
| 670 | Alias for `mapfile`.
|
| 671 |
|
| 672 | ### mapfile
|
| 673 |
|
| 674 | mapfile FLAG* ARRAY?
|
| 675 |
|
| 676 | Reads lines from stdin into the variable named ARRAY (default
|
| 677 | `${MAPFILE[@]}`).
|
| 678 |
|
| 679 | Flags:
|
| 680 |
|
| 681 | -t Remove the trailing newline from every line
|
| 682 | <!--
|
| 683 | -d CHAR use CHAR as delimiter, instead of the default newline
|
| 684 | -n NUM copy up to NUM lines
|
| 685 | -O NUM begins copying lines at the NUM element of the array
|
| 686 | -s NUM discard the first NUM lines
|
| 687 | -u FD read from FD file descriptor instead of the standard input
|
| 688 | -C CMD run CMD every NUM lines specified in -c
|
| 689 | -c NUM every NUM lines, the CMD command in C will be run
|
| 690 | -->
|
| 691 |
|
| 692 | ## Run Code
|
| 693 |
|
| 694 | These builtins accept shell code and run it.
|
| 695 |
|
| 696 | ### source
|
| 697 |
|
| 698 | source SCRIPT ARG*
|
| 699 |
|
| 700 | Executes SCRIPT with given ARGs in the context of the current shell. It will
|
| 701 | modify existing variables.
|
| 702 |
|
| 703 | ### eval
|
| 704 |
|
| 705 | eval ARG+
|
| 706 |
|
| 707 | Creates a string by joining ARGs with a space, then runs it as a shell command.
|
| 708 |
|
| 709 | Example:
|
| 710 |
|
| 711 | # Create the string echo "hello $name" and run it.
|
| 712 | a='echo'
|
| 713 | b='"hello $name"'
|
| 714 | eval $a $b
|
| 715 |
|
| 716 | Tips:
|
| 717 |
|
| 718 | - Using `eval` can confuse code and user-supplied data, leading to [security
|
| 719 | issues][].
|
| 720 | - Prefer passing single string ARG to `eval`.
|
| 721 |
|
| 722 | [security issues]: https://mywiki.wooledge.org/BashFAQ/048
|
| 723 |
|
| 724 | YSH eval:
|
| 725 |
|
| 726 | var myblock = ^(echo hi)
|
| 727 | eval (myblock) # => hi
|
| 728 |
|
| 729 |
|
| 730 | ### trap
|
| 731 |
|
| 732 | trap FLAG* CMD SIGNAL*
|
| 733 |
|
| 734 | Registers the shell string CMD to be run after the SIGNALs are received. If
|
| 735 | the CMD is empty, then the signal is ignored.
|
| 736 |
|
| 737 | Flags:
|
| 738 |
|
| 739 | -l Lists all signals and their signal number
|
| 740 | -p Prints a list of the installed signal handlers
|
| 741 |
|
| 742 | Tip:
|
| 743 |
|
| 744 | Prefer passing the name of a shell function to `trap`.
|
| 745 |
|
| 746 | ## Set Options
|
| 747 |
|
| 748 | The `set` and `shopt` builtins set global shell options. YSH code should use
|
| 749 | the more natural `shopt`.
|
| 750 |
|
| 751 | ### set
|
| 752 |
|
| 753 | set FLAG* ARG*
|
| 754 |
|
| 755 | Sets global shell options. Short style:
|
| 756 |
|
| 757 | set -e
|
| 758 |
|
| 759 | Long style:
|
| 760 |
|
| 761 | set -o errexit
|
| 762 |
|
| 763 | Set the arguments array:
|
| 764 |
|
| 765 | set -- 1 2 3
|
| 766 |
|
| 767 | ### shopt
|
| 768 |
|
| 769 | shopt FLAG* OPTION* BLOCK?
|
| 770 |
|
| 771 | Sets global shell options.
|
| 772 |
|
| 773 | Flags:
|
| 774 |
|
| 775 | -s --set Turn the named options on
|
| 776 | -u --unset Turn the named options off
|
| 777 | -p Print option values
|
| 778 | -o Use older set of options, normally controlled by 'set -o'
|
| 779 | -q Return 0 if the option is true, else 1
|
| 780 |
|
| 781 | Examples:
|
| 782 |
|
| 783 | shopt --set errexit
|
| 784 |
|
| 785 | You can set or unset multiple options with the groups `strict:all`,
|
| 786 | `ysh:upgrade`, and `ysh:all`.
|
| 787 |
|
| 788 | If a block is passed, then the mutated options are pushed onto a stack, the
|
| 789 | block is executed, and then options are restored to their original state.
|
| 790 |
|
| 791 | ## Working Dir
|
| 792 |
|
| 793 | These 5 builtins deal with the working directory of the shell.
|
| 794 |
|
| 795 | ### cd
|
| 796 |
|
| 797 | cd FLAG* DIR
|
| 798 |
|
| 799 | Changes the working directory of the current shell process to DIR.
|
| 800 |
|
| 801 | If DIR isn't specified, change to `$HOME`. If DIR is `-`, change to `$OLDPWD`
|
| 802 | (a variable that the sets to the previous working directory.)
|
| 803 |
|
| 804 | Flags:
|
| 805 |
|
| 806 | -L Follow symbolic links, i.e. change to the TARGET of the symlink.
|
| 807 | (default).
|
| 808 | -P Don't follow symbolic links.
|
| 809 |
|
| 810 | ### pwd
|
| 811 |
|
| 812 | pwd FLAG*
|
| 813 |
|
| 814 | Prints the current working directory.
|
| 815 |
|
| 816 | Flags:
|
| 817 |
|
| 818 | -L Follow symbolic links if present (default)
|
| 819 | -P Don't follow symbolic links. Print the link instead of the target.
|
| 820 |
|
| 821 | ### pushd
|
| 822 |
|
| 823 | <!--pushd FLAGS DIR-->
|
| 824 | pushd DIR
|
| 825 | <!--pushd +/-NUM-->
|
| 826 |
|
| 827 | Add DIR to the directory stack, then change the working directory to DIR.
|
| 828 | Typically used with `popd` and `dirs`.
|
| 829 |
|
| 830 | <!--FLAGS:
|
| 831 | -n Don't change the working directory, just manipulate the stack
|
| 832 | NUM:
|
| 833 | Rotates the stack the number of places specified. Eg, given the stack
|
| 834 | '/foo /bar /baz', where '/foo' is the top of the stack, pushd +1 will move
|
| 835 | it to the bottom, '/bar /baz /foo'-->
|
| 836 |
|
| 837 | ### popd
|
| 838 |
|
| 839 | popd
|
| 840 |
|
| 841 | Removes a directory from the directory stack, and changes the working directory
|
| 842 | to it. Typically used with `pushd` and `dirs`.
|
| 843 |
|
| 844 | ### dirs
|
| 845 |
|
| 846 | dirs FLAG*
|
| 847 |
|
| 848 | Shows the contents of the directory stack. Typically used with `pushd` and
|
| 849 | `popd`.
|
| 850 |
|
| 851 | Flags:
|
| 852 |
|
| 853 | -c Clear the dir stack.
|
| 854 | -l Show the dir stack, but with the real path instead of ~.
|
| 855 | -p Show the dir stack, but formatted as one line per entry.
|
| 856 | -v Like -p, but numbering each line.
|
| 857 |
|
| 858 | ## Completion
|
| 859 |
|
| 860 | These builtins implement our bash-compatible autocompletion system.
|
| 861 |
|
| 862 | ### complete
|
| 863 |
|
| 864 | Registers completion policies for different commands.
|
| 865 |
|
| 866 | ### compgen
|
| 867 |
|
| 868 | Generates completion candidates inside a user-defined completion function.
|
| 869 |
|
| 870 | It can also be used in scripts, i.e. outside a completion function.
|
| 871 |
|
| 872 | ### compopt
|
| 873 |
|
| 874 | Changes completion options inside a user-defined completion function.
|
| 875 |
|
| 876 | ### compadjust
|
| 877 |
|
| 878 | Adjusts `COMP_ARGV` according to specified delimiters, and optionally set
|
| 879 | variables cur, prev, words (an array), and cword. May also set 'split'.
|
| 880 |
|
| 881 | This is an OSH extension that makes it easier to run the bash-completion
|
| 882 | project.
|
| 883 |
|
| 884 | ### compexport
|
| 885 |
|
| 886 | Complete an entire shell command string. For example,
|
| 887 |
|
| 888 | compexport -c 'echo $H'
|
| 889 |
|
| 890 | will complete variables like `$HOME`. And
|
| 891 |
|
| 892 | compexport -c 'ha'
|
| 893 |
|
| 894 | will complete builtins like `hay`, as well as external commands.
|
| 895 |
|
| 896 |
|
| 897 | ## Shell Process
|
| 898 |
|
| 899 | These builtins mutate the state of the shell process.
|
| 900 |
|
| 901 | ### exec
|
| 902 |
|
| 903 | exec BIN_PATH ARG*
|
| 904 |
|
| 905 | Replaces the running shell with the binary specified, which is passed ARGs.
|
| 906 | BIN_PATH must exist on the file system; i.e. it can't be a shell builtin or
|
| 907 | function.
|
| 908 |
|
| 909 | ### umask
|
| 910 |
|
| 911 | umask MODE?
|
| 912 |
|
| 913 | Sets the bit mask that determines the permissions for new files and
|
| 914 | directories. The mask is subtracted from 666 for files and 777 for
|
| 915 | directories.
|
| 916 |
|
| 917 | Oils currently supports writing masks in octal.
|
| 918 |
|
| 919 | If no MODE, show the current mask.
|
| 920 |
|
| 921 | ### ulimit
|
| 922 |
|
| 923 | ulimit --all
|
| 924 | ulimit -a
|
| 925 | ulimit FLAGS* -RESOURCE_FLAG VALUE?
|
| 926 |
|
| 927 | ulimit FLAGS* VALUE? # discouraged
|
| 928 |
|
| 929 | Show and modify process resource limits.
|
| 930 |
|
| 931 | Flags:
|
| 932 |
|
| 933 | -S for soft limit
|
| 934 | -H for hard limit
|
| 935 |
|
| 936 | -c -d -f ... # ulimit --all shows all resource flags
|
| 937 |
|
| 938 | Show a table of resources:
|
| 939 |
|
| 940 | ulimit --all
|
| 941 | ulimit -a
|
| 942 |
|
| 943 | For example, the table shows that `-n` is the flag that controls the number
|
| 944 | file descriptors, the soft and hard limit for `-n`, and the multiplication
|
| 945 | "factor" for the integer VALUE you pass.
|
| 946 |
|
| 947 | ---
|
| 948 |
|
| 949 | Here are examples of using resource flags.
|
| 950 |
|
| 951 | Get the soft limit for the number of file descriptors:
|
| 952 |
|
| 953 | ulimit -S -n
|
| 954 | ulimit -n # same thing
|
| 955 |
|
| 956 | Get the hard limit:
|
| 957 |
|
| 958 | ulimit -H -n
|
| 959 |
|
| 960 | Set the soft or hard limit:
|
| 961 |
|
| 962 | ulimit -S -n 100
|
| 963 | ulimit -H -n 100
|
| 964 |
|
| 965 | Set both limits:
|
| 966 |
|
| 967 | ulimit -n 100
|
| 968 |
|
| 969 | A special case that's discouraged: with no resource flag, `-f` is assumed:
|
| 970 |
|
| 971 | ulimit # equivalent to ulimit -f
|
| 972 | ulimit 100 # equivalent to ulimit -f 100
|
| 973 |
|
| 974 | ### times
|
| 975 |
|
| 976 | times
|
| 977 |
|
| 978 | Shows the user and system time used by the shell and its child processes.
|
| 979 |
|
| 980 | ## Child Process
|
| 981 |
|
| 982 | ### jobs
|
| 983 |
|
| 984 | jobs
|
| 985 |
|
| 986 | Shows all jobs running in the shell and their status.
|
| 987 |
|
| 988 | ### wait
|
| 989 |
|
| 990 | wait FLAG* ARG
|
| 991 |
|
| 992 | Wait for processes to exit.
|
| 993 |
|
| 994 | If the ARG is a PID, wait only for that job, and return its status.
|
| 995 |
|
| 996 | If there's no ARG, wait for all child processes.
|
| 997 |
|
| 998 | <!--
|
| 999 | The ARG can be a PID (tracked by the kernel), or a job number (tracked by the
|
| 1000 | shell). Specify jobs with the syntax `%jobnumber`.
|
| 1001 | -->
|
| 1002 |
|
| 1003 | Flags:
|
| 1004 |
|
| 1005 | -n Wait for the next process to exit, rather than a specific process.
|
| 1006 |
|
| 1007 | Wait can be interrupted by a signal, in which case the exit code indicates the
|
| 1008 | signal number.
|
| 1009 |
|
| 1010 | ### fg
|
| 1011 |
|
| 1012 | fg JOB?
|
| 1013 |
|
| 1014 | Returns a job running in the background to the foreground. If no JOB is
|
| 1015 | specified, use the latest job.
|
| 1016 |
|
| 1017 | <!--<h4 id="bg">bg</h4>
|
| 1018 |
|
| 1019 | The bg builtin resumes suspend job, while keeping it in the background.
|
| 1020 |
|
| 1021 | bg JOB?
|
| 1022 |
|
| 1023 | JOB:
|
| 1024 | Job ID to be resumed in the background. If none is specified, the latest job
|
| 1025 | is chosen. -->
|
| 1026 |
|
| 1027 | ## External
|
| 1028 |
|
| 1029 | ### test
|
| 1030 |
|
| 1031 | test OP ARG
|
| 1032 | test ARG OP ARG
|
| 1033 | [ OP ARG ] # [ is an alias for test that requires closing ]
|
| 1034 | [ ARG OP ARG ]
|
| 1035 |
|
| 1036 | Evaluates a conditional expression and returns 0 (true) or 1 (false).
|
| 1037 |
|
| 1038 | Note that [ is the name of a builtin, not an operator in the language. Use
|
| 1039 | 'test' to avoid this confusion.
|
| 1040 |
|
| 1041 | String expressions:
|
| 1042 |
|
| 1043 | -n STR True if STR is not empty.
|
| 1044 | 'test STR' is usually equivalent, but discouraged.
|
| 1045 | -z STR True if STR is empty.
|
| 1046 | STR1 = STR2 True if the strings are equal.
|
| 1047 | STR1 != STR2 True if the strings are not equal.
|
| 1048 | STR1 < STR2 True if STR1 sorts before STR2 lexicographically.
|
| 1049 | STR1 > STR2 True if STR1 sorts after STR2 lexicographically.
|
| 1050 | Note: < and > should be quoted like \< and \>
|
| 1051 |
|
| 1052 | File expressions:
|
| 1053 |
|
| 1054 | -a FILE Synonym for -e.
|
| 1055 | -b FILE True if FILE is a block special file.
|
| 1056 | -c FILE True if FILE is a character special file.
|
| 1057 | -d FILE True if FILE is a directory.
|
| 1058 | -e FILE True if FILE exists.
|
| 1059 | -f FILE True if FILE is a regular file.
|
| 1060 | -g FILE True if FILE has the sgid bit set.
|
| 1061 | -G FILE True if current user's group is also FILE's group.
|
| 1062 | -h FILE True if FILE is a symbolic link.
|
| 1063 | -L FILE True if FILE is a symbolic link.
|
| 1064 | -k FILE True if FILE has the sticky bit set.
|
| 1065 | -O FILE True if current user is the file owner.
|
| 1066 | -p FILE True if FILE is a named pipe (FIFO).
|
| 1067 | -r FILE True if FILE is readable.
|
| 1068 | -s FILE True if FILE has size bigger than 0.
|
| 1069 | -S FILE True if FILE is a socket file.
|
| 1070 | -t FD True if file descriptor FD is open and refers to a terminal.
|
| 1071 | -u FILE True if FILE has suid bit set.
|
| 1072 | -w FILE True if FILE is writable.
|
| 1073 | -x FILE True if FILE is executable.
|
| 1074 | FILE1 -nt FILE2 True if FILE1 is newer than FILE2 (mtime).
|
| 1075 | FILE1 -ot FILE2 True if FILE1 is older than FILE2 (mtime).
|
| 1076 | FILE1 -ef FILE2 True if FILE1 is a hard link to FILE2.
|
| 1077 | <!-- -N FILE True if FILE was modified since last read (mtime newer than atime).-->
|
| 1078 |
|
| 1079 | Arithmetic expressions coerce arguments to integers, then compare:
|
| 1080 |
|
| 1081 | INT1 -eq INT2 True if they're equal.
|
| 1082 | INT1 -ne INT2 True if they're not equal.
|
| 1083 | INT1 -lt INT2 True if INT1 is less than INT2.
|
| 1084 | INT1 -le INT2 True if INT1 is less or equal than INT2.
|
| 1085 | INT1 -gt INT2 True if INT1 is greater than INT2.
|
| 1086 | INT1 -ge INT2 True if INT1 is greater or equal than INT2.
|
| 1087 |
|
| 1088 | Other expressions:
|
| 1089 |
|
| 1090 | -o OPTION True if the shell option OPTION is set.
|
| 1091 | -v VAR True if the variable VAR is set.
|
| 1092 |
|
| 1093 | The test builtin also supports POSIX conditionals like -a, -o, !, and ( ), but
|
| 1094 | these are discouraged.
|
| 1095 |
|
| 1096 | <!-- -R VAR True if the variable VAR has been set and is a nameref variable. -->
|
| 1097 |
|
| 1098 | Oils supports these long flags:
|
| 1099 |
|
| 1100 | --dir same as -d
|
| 1101 | --exists same as -e
|
| 1102 | --file same as -f
|
| 1103 | --symlink same as -L
|
| 1104 |
|
| 1105 | ### getopts
|
| 1106 |
|
| 1107 | getopts SPEC VAR ARG*
|
| 1108 |
|
| 1109 | A single iteration of flag parsing. The SPEC is a sequence of flag characters,
|
| 1110 | with a trailing `:` to indicate that the flag takes an argument:
|
| 1111 |
|
| 1112 | ab # accept -a and -b
|
| 1113 | xy:z # accept -x, -y arg, and -z
|
| 1114 |
|
| 1115 | The input is `"$@"` by default, unless ARGs are passed.
|
| 1116 |
|
| 1117 | On each iteration, the flag character is stored in VAR. If the flag has an
|
| 1118 | argument, it's stored in `$OPTARG`. When an error occurs, VAR is set to `?`
|
| 1119 | and `$OPTARG` is unset.
|
| 1120 |
|
| 1121 | Returns 0 if a flag is parsed, or 1 on end of input or another error.
|
| 1122 |
|
| 1123 | Example:
|
| 1124 |
|
| 1125 | while getopts "ab:" flag; do
|
| 1126 | case $flag in
|
| 1127 | a) flag_a=1 ;;
|
| 1128 | b) flag_b=$OPTARG" ;;
|
| 1129 | '?') echo 'Invalid Syntax'; break ;;
|
| 1130 | esac
|
| 1131 | done
|
| 1132 |
|
| 1133 | Notes:
|
| 1134 | - `$OPTIND` is initialized to 1 every time a shell starts, and is used to
|
| 1135 | maintain state between invocations of `getopts`.
|
| 1136 | - The characters `:` and `?` can't be flags.
|
| 1137 |
|
| 1138 | ### kill
|
| 1139 |
|
| 1140 | Unimplemented.
|
| 1141 |
|
| 1142 | <!-- Note: 'kill' accepts job control syntax -->
|
| 1143 |
|
| 1144 | ## Introspection
|
| 1145 |
|
| 1146 | <h3 id="help" class="osh-topic ysh-topic" oils-embed="1">
|
| 1147 | help
|
| 1148 | </h3>
|
| 1149 |
|
| 1150 | <!-- pre-formatted for help builtin -->
|
| 1151 |
|
| 1152 | ```
|
| 1153 | Usage: help TOPIC?
|
| 1154 |
|
| 1155 | Examples:
|
| 1156 |
|
| 1157 | help # this help
|
| 1158 | help echo # help on the 'echo' builtin
|
| 1159 | help command-sub # help on command sub $(date)
|
| 1160 |
|
| 1161 | help oils-usage # identical to oils-for-unix --help
|
| 1162 | help osh-usage # osh --help
|
| 1163 | help ysh-usage # ysh --help
|
| 1164 | ```
|
| 1165 |
|
| 1166 | ### hash
|
| 1167 |
|
| 1168 | hash
|
| 1169 |
|
| 1170 | Display information about remembered commands.
|
| 1171 |
|
| 1172 | hash FLAG* CMD+
|
| 1173 |
|
| 1174 | Determine the locations of commands using `$PATH`, and remember them.
|
| 1175 |
|
| 1176 | Flag:
|
| 1177 |
|
| 1178 | -r Discard all remembered locations.
|
| 1179 | <!-- -d Discard the remembered location of each NAME.
|
| 1180 | -l Display output in a format reusable as input.
|
| 1181 | -p PATH Inhibit path search, PATH is used as location for NAME.
|
| 1182 | -t Print the full path of one or more NAME.-->
|
| 1183 |
|
| 1184 | ### cmd/type
|
| 1185 |
|
| 1186 | type FLAG* NAME+
|
| 1187 |
|
| 1188 | Print the type of each NAME, if it were the first word of a command. Is it a
|
| 1189 | shell keyword, builtin command, shell function, alias, or executable file on
|
| 1190 | $PATH?
|
| 1191 |
|
| 1192 | Flags:
|
| 1193 |
|
| 1194 | -a Show all possible candidates, not just the first one
|
| 1195 | -f Don't search for shell functions
|
| 1196 | -P Only search for executable files
|
| 1197 | -t Print a single word: alias, builtin, file, function, or keyword
|
| 1198 |
|
| 1199 | Similar names: [type][]
|
| 1200 |
|
| 1201 | [type]: chap-index.html#type
|
| 1202 |
|
| 1203 | <!-- TODO:
|
| 1204 | - procs are counted as shell functions, should be their own thing
|
| 1205 | - Hay nodes ('hay define x') also live in the first word namespace, and should
|
| 1206 | be recognized
|
| 1207 | -->
|
| 1208 |
|
| 1209 | Modeled after the [bash `type`
|
| 1210 | builtin](https://www.gnu.org/software/bash/manual/bash.html#index-type).
|
| 1211 |
|
| 1212 | ## Word Lookup
|
| 1213 |
|
| 1214 | ### command
|
| 1215 |
|
| 1216 | command FLAG* CMD ARG*
|
| 1217 |
|
| 1218 | Look up CMD as a shell builtin or executable file, and execute it with the
|
| 1219 | given ARGs. That is, the lookup ignores shell functions named CMD.
|
| 1220 |
|
| 1221 | Flags:
|
| 1222 |
|
| 1223 | -v Instead of executing CMD, print a description of it.
|
| 1224 | Similar to the 'type' builtin.
|
| 1225 | <!-- -p Use a default value for PATH that is guaranteed to find all of the
|
| 1226 | standard utilities.
|
| 1227 | -V Print a more verbose description of CMD.-->
|
| 1228 |
|
| 1229 | ### builtin
|
| 1230 |
|
| 1231 | builtin CMD ARG*
|
| 1232 |
|
| 1233 | Look up CMD as a shell builtin, and execute it with the given ARGs. That is,
|
| 1234 | the lookup ignores shell functions and executables named CMD.
|
| 1235 |
|
| 1236 | ## Interactive
|
| 1237 |
|
| 1238 | ### alias
|
| 1239 |
|
| 1240 | alias NAME=CODE
|
| 1241 |
|
| 1242 | Make NAME a shortcut for executing CODE, e.g. `alias hi='echo hello'`.
|
| 1243 |
|
| 1244 | alias NAME
|
| 1245 |
|
| 1246 | Show the value of this alias.
|
| 1247 |
|
| 1248 | alias
|
| 1249 |
|
| 1250 | Show a list of all aliases.
|
| 1251 |
|
| 1252 | Tips:
|
| 1253 |
|
| 1254 | Prefer shell functions like:
|
| 1255 |
|
| 1256 | ls() {
|
| 1257 | command ls --color "$@"
|
| 1258 | }
|
| 1259 |
|
| 1260 | to aliases like:
|
| 1261 |
|
| 1262 | alias ls='ls --color'
|
| 1263 |
|
| 1264 | Functions are less likely to cause parsing problems.
|
| 1265 |
|
| 1266 | - Quoting like `\ls` or `'ls'` disables alias expansion
|
| 1267 | - To remove an existing alias, use [unalias](chap-builtin-cmd.html#unalias).
|
| 1268 |
|
| 1269 | ### unalias
|
| 1270 |
|
| 1271 | unalias NAME
|
| 1272 |
|
| 1273 | Remove the alias NAME.
|
| 1274 |
|
| 1275 | <!--Flag:
|
| 1276 |
|
| 1277 | -a Removes all existing aliases.-->
|
| 1278 |
|
| 1279 | ### history
|
| 1280 |
|
| 1281 | history FLAG*
|
| 1282 |
|
| 1283 | Display and manipulate the shell's history entries.
|
| 1284 |
|
| 1285 | history NUM
|
| 1286 |
|
| 1287 | Show the last NUM history entries.
|
| 1288 |
|
| 1289 | Flags:
|
| 1290 |
|
| 1291 | -c Clears the history.
|
| 1292 | -d POS Deletes the history entry at position POS.
|
| 1293 | <!-- -a
|
| 1294 | -n
|
| 1295 | -r
|
| 1296 | -w
|
| 1297 | -p
|
| 1298 | -s -->
|
| 1299 |
|
| 1300 |
|
| 1301 | ## Unsupported
|
| 1302 |
|
| 1303 | ### enable
|
| 1304 |
|
| 1305 | Bash has this, but OSH won't implement it.
|
| 1306 |
|
| 1307 |
|
| 1308 | ## Args Parser
|
| 1309 |
|
| 1310 | YSH includes a command-line argument parsing utility called `parseArgs`. This
|
| 1311 | is intended to be used for command-line interfaces to YSH programs.
|
| 1312 |
|
| 1313 | To use it, first import `args.ysh`:
|
| 1314 |
|
| 1315 | source --builtin args.ysh
|
| 1316 |
|
| 1317 | Then, create an argument parser **spec**ification:
|
| 1318 |
|
| 1319 | parser (&spec) {
|
| 1320 | flag -v --verbose (help="Verbosely") # default is Bool, false
|
| 1321 |
|
| 1322 | flag -P --max-procs ('int', default=-1, help='''
|
| 1323 | Run at most P processes at a time
|
| 1324 | ''')
|
| 1325 |
|
| 1326 | flag -i --invert ('bool', default=true, help='''
|
| 1327 | Long multiline
|
| 1328 | Description
|
| 1329 | ''')
|
| 1330 |
|
| 1331 | arg src (help='Source')
|
| 1332 | arg dest (help='Dest')
|
| 1333 |
|
| 1334 | rest files
|
| 1335 | }
|
| 1336 |
|
| 1337 | Finally, parse `ARGV` (or any other array of strings) with:
|
| 1338 |
|
| 1339 | var args = parseArgs(spec, ARGV)
|
| 1340 |
|
| 1341 | The returned `args` is a `Dict` containing key-value pairs with the parsed
|
| 1342 | values (or defaults) for each flag and argument. For example, given
|
| 1343 | `ARGV = :| mysrc -P 12 mydest a b c |`, `args` would be:
|
| 1344 |
|
| 1345 | {
|
| 1346 | "verbose": false,
|
| 1347 | "max-procs": 12,
|
| 1348 | "invert": true,
|
| 1349 | "src": "mysrc",
|
| 1350 | "dest": "mydest",
|
| 1351 | "files": ["a", "b", "c"]
|
| 1352 | }
|
| 1353 |
|
| 1354 | ### parser
|
| 1355 |
|
| 1356 | `parseArgs()` requires a parser specification to indicate how to parse the
|
| 1357 | `ARGV` array. This specification should be constructed using the `parser` proc.
|
| 1358 |
|
| 1359 | parser (&spec) {
|
| 1360 | flag -f --my-flag
|
| 1361 | arg myarg
|
| 1362 | rest otherArgs
|
| 1363 | }
|
| 1364 |
|
| 1365 | In the above example, `parser` takes in a place `&spec`, which will store the
|
| 1366 | resulting specification and a block which is evaluated to build that
|
| 1367 | specification.
|
| 1368 |
|
| 1369 | Inside of a `parser` block, you should call the following procs:
|
| 1370 |
|
| 1371 | - `flag` to add `--flag` options
|
| 1372 | - `arg` to add positional arguments
|
| 1373 | - `rest` to capture remaining positional arguments into a list
|
| 1374 |
|
| 1375 | `parser` will validate the parser specification for errors such as duplicate
|
| 1376 | flag or argument names.
|
| 1377 |
|
| 1378 | parser (&spec) {
|
| 1379 | flag -n --name
|
| 1380 | flag -n --name # Duplicate!
|
| 1381 | }
|
| 1382 |
|
| 1383 | # => raises "Duplicate flag/arg name 'name' in spec" (status = 3)
|
| 1384 |
|
| 1385 | ### flag
|
| 1386 |
|
| 1387 | `flag` should be called within a `parser` block.
|
| 1388 |
|
| 1389 | parser (&spec) {
|
| 1390 | flag -v --verbose
|
| 1391 | }
|
| 1392 |
|
| 1393 | The above example declares a flag "--verbose" and a short alias "-v".
|
| 1394 | `parseArgs()` will then store a boolean value under `args.verbose`:
|
| 1395 | - `true` if the flag was passed at least once
|
| 1396 | - `false` otherwise
|
| 1397 |
|
| 1398 | Flags can also accept values. For example, if you wanted to accept an integer count:
|
| 1399 |
|
| 1400 | parser (&spec) {
|
| 1401 | flag -N --count ('int')
|
| 1402 | }
|
| 1403 |
|
| 1404 | Calling `parseArgs` with `ARGV = :| -n 5 |` or `ARGV = :| --count 5 |` will
|
| 1405 | store the integer `5` under `args.count`. If the user passes in a non-integer
|
| 1406 | value like `ARGV = :| --count abc |`, `parseArgs` will raise an error.
|
| 1407 |
|
| 1408 | Default values for an argument can be set with the `default` named argument.
|
| 1409 |
|
| 1410 | parser (&spec) {
|
| 1411 | flag -N --count ('int', default=2)
|
| 1412 |
|
| 1413 | # Boolean flags can be given default values too
|
| 1414 | flag -O --optimize ('bool', default=true)
|
| 1415 | }
|
| 1416 |
|
| 1417 | var args = parseArgs(spec, :| -n 3 |)
|
| 1418 | # => args.count = 2
|
| 1419 | # => args.optimize = true
|
| 1420 |
|
| 1421 | Each name passed to `flag` must be unique to that specific `parser`. Calling
|
| 1422 | `flag` with the same name twice will raise an error inside of `parser`.
|
| 1423 |
|
| 1424 | <!-- TODO: how can we explicitly pass false to a boolean flag? -->
|
| 1425 | <!-- TODO: how about --no-XXXX variants of flags? -->
|
| 1426 |
|
| 1427 | ### arg
|
| 1428 |
|
| 1429 | `arg` should be called within a `parser` block.
|
| 1430 |
|
| 1431 | parser (&spec) {
|
| 1432 | arg query
|
| 1433 | arg path
|
| 1434 | }
|
| 1435 |
|
| 1436 | The above example declares two positional arguments called "query" and "path".
|
| 1437 | `parseArgs()` will then store strings under `args.query` and `args.path`. Order
|
| 1438 | matters, so the first positional argument will be stored to `query` and the
|
| 1439 | second to `path`. If not enough positional arguments are passed, then
|
| 1440 | `parseArgs` will raise an error.
|
| 1441 |
|
| 1442 | Similar to `flag`, each `arg` name must be unique. Calling `arg` with the same
|
| 1443 | name twice will cause `parser` to raise an error.
|
| 1444 |
|
| 1445 | ### rest
|
| 1446 |
|
| 1447 | `rest` should be called within a `parser` block.
|
| 1448 |
|
| 1449 | parser (&spec) {
|
| 1450 | arg query
|
| 1451 | rest files
|
| 1452 | }
|
| 1453 |
|
| 1454 | Capture zero or more positional arguments not already captured by `arg`. So,
|
| 1455 | for `ARGV = :| hello file.txt message.txt README.md |`, we would have
|
| 1456 | `args.query = "file.txt"` and `args.files = ["file.txt", "message.txt",
|
| 1457 | "README.md"]`.
|
| 1458 |
|
| 1459 | Without rest, passing extraneous arguments will raise an error in
|
| 1460 | `parseArgs()`.
|
| 1461 |
|
| 1462 | `rest` can only be called _once_ within a `parser`. Calling it multiple times
|
| 1463 | will raise an error in `parser`.
|
| 1464 |
|
| 1465 | ### parseArgs()
|
| 1466 |
|
| 1467 | Given a parser specification `spec` produced by `parser`, parse a list of
|
| 1468 | strings (usually `ARGV`.)
|
| 1469 |
|
| 1470 | var args = parseArgs(spec, ARGV)
|
| 1471 |
|
| 1472 | The returned `args` is a dictionary mapping the names of each `arg`, `flag` and
|
| 1473 | `rest` to their captured values. (See the example at the [start of this
|
| 1474 | topic](#Args-Parser).)
|
| 1475 |
|
| 1476 | `parseArgs` will raise an error if the `ARGV` is invalid per the parser
|
| 1477 | specification. For example, if it's missing a required positional argument:
|
| 1478 |
|
| 1479 | parser (&spec) {
|
| 1480 | arg path
|
| 1481 | }
|
| 1482 |
|
| 1483 | var args = parseArgs(spec, [])
|
| 1484 | # => raises an error about the missing 'path' (status = 2)
|
| 1485 |
|
| 1486 | <!--
|
| 1487 | TODO: Document chaining parsers / sub-commands
|
| 1488 | - Either will allow parser nesting
|
| 1489 | - Or can use `rest rest` and `parseArgs` again on `rest`
|
| 1490 | TODO: Document the help named argument. Punting while we do not generate help messages
|
| 1491 | -->
|