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| -rw-r--r-- | README.md | 63 |
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@@ -14,19 +14,64 @@ command is optional. For example, a pattern string may look like ‘`x/[a-z]+/ g.foo. v/bar/`’. -The available operators are ‘g’, ‘v’, and ‘x’. The ‘x' operator iterates -over all matches of the corresponding regex. This means that to print -all numbers in a file, you can use the pattern string ‘`x/[0-9]+/`’. The -‘g’ and ‘v’ operators are filters. The ‘g’ operator discards all results -that don’t match the given regex, while the ‘v’ operator discards all -results that *do* match the given regex. This means that to select all -numbers in a file that contain a ‘3’ but are not ‘1337’, you can use the -pattern string ‘`x/[0-9]+/ g/3/ v/^1337$/`’. +The available operators are ‘g’, ‘v’, ‘x’, and ‘y’. The ‘g’ and ‘v’ +operators are filter operators, while ‘x’ and ‘y’ are selection +operators. + +You probably want to begin your pattern with a selection operator. By +default the entire contents of the file you’re searching through will be +selected, but you probably want to shrink that down to a specific query. +With ‘x’ you can specify what text you want to select in the file. For +example ‘`x/[0-9]+/`’ will select all numbers: + +```sh +echo 'foo12bar34baz' | grab 'x/[0-9]+/' +# ⇒ 12 +# ⇒ 34 +``` + +The ‘y’ operator works in reverse, selecting everything that _doesn’t_ +match the given regex: + +```sh +echo 'foo12bar34baz' | grab 'y/[0-9]+/' +# ⇒ foo +# ⇒ bar +# ⇒ baz +``` + +You can additionally use filter operators to keep or discard certain +results. The ‘g’ operator will filter out any results that don’t match +the given regex, while the ‘v’ operator will do the opposite. To select +all numbers that contain a ‘3’ we can thus do: + +``` sh +echo 'foo12bar34baz' | grab 'x/[0-9]+/ g/3/' +# ⇒ 34 + +# If we had used ‘x’ instead of ‘g’, the result would have just been ‘3’. +# Filter operators do not modify the selections; they merely filter them. +``` + +Likewise to select all numbers that don’t contain a ‘3’: + +```sh +echo 'foo12bar34baz' | grab 'x/[0-9]+/ v/3/' +# ⇒ 12 +``` + +You can also chain these together. To get all numbers in a file that +contain a ‘3’ but aren’t the specific number ‘1337’, we could do the +following: + +```sh +grab 'x/[0-9]+/ g/3/ v/^1337$/' /foo/bar +``` ## Examples -Get a list of your CPU flags. +### Get a list of your CPU flags. ```sh # With Grep |