| 1 | # Command language
|
| 2 |
|
| 3 | ## Simple commands
|
| 4 |
|
| 5 | ### variable declaration and mutation
|
| 6 |
|
| 7 | # Declaring a variable does NOT looks like this:
|
| 8 | # Variable="Some string" => name=val isn't allowed when shopt 'parse_equals' is on.
|
| 9 | # Hint: add 'env' before it, or spaces around =
|
| 10 |
|
| 11 | # Nor like this
|
| 12 | # Variable = "Some string" # => same error
|
| 13 |
|
| 14 | # this is the preferred way
|
| 15 | # no need for capitalization like in bash
|
| 16 | var variable = "Some string"
|
| 17 |
|
| 18 | # also valid but not idomatic
|
| 19 | set variable = "Another string"
|
| 20 |
|
| 21 | # const to declare a constant
|
| 22 | const immutable = "definitive"
|
| 23 |
|
| 24 | # this will not work
|
| 25 | # set immutable = "not so sure" => Can't modify constant 'immutable'
|
| 26 |
|
| 27 | # mutate a variable with setvar
|
| 28 | var new = "a brave new world"
|
| 29 | setvar new = "perhaps it's already here"
|
| 30 | echo $new
|
| 31 |
|
| 32 | # setglobal will create or mutate a global variable
|
| 33 | setglobal the_answer = 42
|
| 34 | echo $the_answer
|
| 35 |
|
| 36 | # there are more ways to set variable by passing them
|
| 37 | # to procs. This will be expanded in the procs section
|
| 38 |
|
| 39 | ### Variable substitution
|
| 40 |
|
| 41 | var regular_string = "I am just a normal string"
|
| 42 | echo $regular_string # quotes not needed
|
| 43 | #### if you want to do string interpolation
|
| 44 | echo "$regular_string and $regular_string"
|
| 45 | #### you need to do it another way if you want to substitute before a _
|
| 46 | # this will not work "$regular_string_"
|
| 47 | # as it will look for the regular_string_ variable
|
| 48 | echo "${regular_string}_" # but this will
|
| 49 |
|
| 50 | ### Parameter expansion works just like in bash
|
| 51 | var some_string = "I am some string"
|
| 52 | echo ${some_string/another/some} # => I am another string
|
| 53 |
|
| 54 | ### Strings
|
| 55 |
|
| 56 | # this will not work
|
| 57 | # echo "\n" => Invalid char escape in double quoted string
|
| 58 | # this prints the characters
|
| 59 | echo '\n'
|
| 60 | # use $ to print a new line
|
| 61 | echo $'\n'
|
| 62 |
|
| 63 | # unicode works like this
|
| 64 | # var unicode = j"mu = \u{3bc}"
|
| 65 | # echo $unicode
|
| 66 |
|
| 67 | # but not like this
|
| 68 | # var unicode = 'mu = \u{3bc}' => Strings with backslashes should look like r'\n', c'\n' or $'\n'
|
| 69 |
|
| 70 | ### builtins
|
| 71 |
|
| 72 | #### echo
|
| 73 | # takes at most 1 argument and prints to stdout
|
| 74 | echo "Hello world!" # => Hello world!
|
| 75 |
|
| 76 | #### write
|
| 77 | # write outputs to stdout
|
| 78 | # write has a -- separator to not confuse command line arguments and what you want to print
|
| 79 | var i_am_a_string = "I'm just a string"
|
| 80 | write -- $i_am_a_string
|
| 81 | # if you have a string with a newline in it
|
| 82 | var i_have_a_newline = $'it\'s true I really do \n'
|
| 83 | # write works well with it, unlike bash's printf
|
| 84 | write -- $i_have_a_newline
|
| 85 | # you can print the content without the newline with -n
|
| 86 | write -n -- $i_have_a_newline
|
| 87 |
|
| 88 | #### test
|
| 89 | # test has been improved to be a little less crytic
|
| 90 |
|
| 91 | # test if something is a directory
|
| 92 | test --dir /tmp || echo "Not a dir"
|
| 93 | test -d /tmp # still works but less readable
|
| 94 |
|
| 95 | # test if something is a file
|
| 96 | test --file /tmp/maybe_a_file || echo "Not a file"
|
| 97 |
|
| 98 | ### Procs
|
| 99 |
|
| 100 | ### think of procs as a better version of bash's functions
|
| 101 | ### use proc for abstraction
|
| 102 | proc abstract() {
|
| 103 | echo "I'm an abstraction"
|
| 104 | }
|
| 105 |
|
| 106 | ### and call it without brackets
|
| 107 | abstract
|
| 108 |
|
| 109 | ### proc can't access variables they are not given as params
|
| 110 | ### proc print_variable() {
|
| 111 | ### echo $some_not_given_variable
|
| 112 | ### }
|
| 113 | ### print_variable
|
| 114 | ### fatal: Undefined variable 'some_not_given_variable'
|
| 115 |
|
| 116 | proc print_variable(passed_variable) {
|
| 117 | echo $passed_variable
|
| 118 | }
|
| 119 |
|
| 120 | ### call procs with arguments without brackets
|
| 121 | var variable_to_pass = "I'm passed"
|
| 122 | print_variable $variable_to_pass
|
| 123 |
|
| 124 | # If you're going to use a shell function or proc in a condition, wrap it with 'try'
|
| 125 | # to avoid a strict_errexit error
|
| 126 | proc myproc {
|
| 127 | echo hi
|
| 128 | return 1
|
| 129 | }
|
| 130 |
|
| 131 | try {
|
| 132 | myproc
|
| 133 | }
|
| 134 | if (_status !== 0) {
|
| 135 | echo failure
|
| 136 | }
|
| 137 |
|
| 138 | ### external commands
|
| 139 |
|
| 140 | ### Ruby like blocks
|
| 141 |
|
| 142 | ## Redirects
|
| 143 |
|
| 144 | ## Pipelines
|
| 145 |
|
| 146 | ## Control flow
|
| 147 |
|
| 148 | ### general
|
| 149 |
|
| 150 | ### use command substitution to assign the result of a command to a variable
|
| 151 | var year = $(date -u +"%Y")
|
| 152 | echo $year
|
| 153 |
|
| 154 | # a failure will exit immediately
|
| 155 | # var year = $(date --wrong-flag +"%Y") => date: illegal option -- -
|
| 156 | # usage: date [-jnRu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ...
|
| 157 | # [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]
|
| 158 | # var year = $(date --wrong-flag "%Y")
|
| 159 | # ^~
|
| 160 | # ./tour.sh:38: fatal: Command sub exited with status 1 (command.Simple)
|
| 161 |
|
| 162 |
|
| 163 | ### if
|
| 164 |
|
| 165 | # if works just like you would expect
|
| 166 |
|
| 167 | if true {
|
| 168 | echo "Here I am!"
|
| 169 | } else {
|
| 170 | echo "I'll never be"
|
| 171 | }
|
| 172 |
|
| 173 | # However be careful, brackets have a special meaning
|
| 174 | # those are for conditionals, you won't be able to
|
| 175 | # run functions inside those
|
| 176 | proc is_it_true() {
|
| 177 | false
|
| 178 | }
|
| 179 | # this won't work
|
| 180 | # if (! is_it_true) {
|
| 181 | # echo "could be anything really"
|
| 182 | # }
|
| 183 | # Syntax error in expression (near Id.Expr_Bang)
|
| 184 | # to make it work you have to 'try' the proc
|
| 185 | # and remove the brackets
|
| 186 |
|
| 187 | try { is_it_true }
|
| 188 | if (_status !== 0) {
|
| 189 | echo "could be anything really"
|
| 190 | }
|
| 191 |
|
| 192 | # an error in a proc will print
|
| 193 | proc err_today() {
|
| 194 | date --wrong-flag
|
| 195 | }
|
| 196 |
|
| 197 | try {
|
| 198 | err_today
|
| 199 | echo "will never be executed"
|
| 200 | }
|
| 201 | if (_status !== 0) {
|
| 202 | # this will also print the proc error
|
| 203 | # date: illegal option -- -
|
| 204 | # usage: date [-jnRu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ...
|
| 205 | # [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]
|
| 206 | echo "there was an error"
|
| 207 | }
|
| 208 |
|
| 209 | ### case
|
| 210 |
|
| 211 | ### for
|
| 212 |
|
| 213 | ### while
|
| 214 |
|
| 215 | ## fork and wait
|
| 216 |
|
| 217 | ## Expression language
|
| 218 |
|
| 219 | ### Eggex
|
| 220 |
|
| 221 | #### matching happens with eggexes, which are a different take on regex
|
| 222 | #### you can use
|
| 223 | #### digit => to match numbers
|
| 224 | #### word => to match any character that is not a space
|
| 225 | #### space => to match all the non word characters (tab, newline...)
|
| 226 | #### dot => to match any character
|
| 227 |
|
| 228 | var s = '123'
|
| 229 | if (s ~ /digit+/) {
|
| 230 | echo 'number'
|
| 231 | }
|
| 232 |
|
| 233 | #### extract a submatch with < >
|
| 234 | #### if ($(date -u +"%Y-%m-%d") ~ /< digit{4} :year> '-' <digit{2} :month>!word<digit{2} :day>/) {
|
| 235 | if ($(date -u +"%Y-%m-%d") ~ /<capture digit{4} as year> '-' <capture digit{2} as month> '-' <capture digit{2} as day>/) {
|
| 236 | # extract a match by number
|
| 237 | const complete_match = _match(0)
|
| 238 | const group_match = _match(1)
|
| 239 | echo $complete_match
|
| 240 | echo $group_match
|
| 241 | }
|