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 |
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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 |
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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 |
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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 |
|
569 | TODO: describe
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570 |
|
571 | ## External Lang
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572 |
|
573 | TODO: when
|
574 |
|
575 |
|
576 | ## I/O
|
577 |
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578 | These builtins take input and output. They're often used with redirects.
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579 |
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580 | ### read
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581 |
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582 | read FLAG* VAR*
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583 |
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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
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589 | [ysh-read](#ysh-read). The `read` builtin is confusing because `-r` needs to
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590 | be explicitly enabled.
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591 |
|
592 | Flags:
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593 |
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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
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596 | -n NUM read up to NUM characters, respecting delimiters
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597 | -p STR print the string PROMPT before reading input
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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
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602 | -u FD read from file descriptor FD instead of 0 (stdin)
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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
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606 | -i STR use STR as the initial text for readline -->
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607 |
|
608 | ### echo
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609 |
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610 | echo FLAG* ARG*
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611 |
|
612 | Prints ARGs to stdout, separated by a space, and terminated by a newline.
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613 |
|
614 | Flags:
|
615 |
|
616 | -e enable interpretation of backslash escapes
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617 | -n omit the trailing newline
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618 | <!-- -E -->
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619 |
|
620 | See [char-escapes](chap-mini-lang.html#char-escapes).
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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.
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646 | %i Same as %d.
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647 | %o Print as unsigned octal number.
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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 | -->
|