Differences between revisions 14 and 16 (spanning 2 versions)
⇤ ← Revision 14 as of 2013-01-14 22:03:43 →
Size: 1555
Editor: ormaaj
Comment: Stupid mksh. Why the does shift throw fatal errors when POSIX doesn't require it to?!? Add "command" workaround (POSIX doesn't require that either, but it works everywhere except mksh).
← Revision 16 as of 2022-11-23 19:29:49 → ⇥
Size: 1777
Editor: GreyCat
Comment: extglobs are only on by default inside [[ ]] in bash 4.1+
Deletions are marked like this. Additions are marked like this.
Line 7: Line 7:
   case "$var" in    case $var in
Line 15: Line 15:
   ${BASH_VERSION+shopt -s extglob}
Line 21: Line 20:
Extended globs are turned on by default inside the `[[` command in bash 4.1 and newer. If you need to target an older version of bash, you will need to turn them on in your script (`shopt -s extglob` outside of all functions or compound commands).
Line 23: Line 24:
    # bash/ksh93/zsh (w/ emulate ksh) #!/usr/bin/env bash
# bash/ksh93
Line 25: Line 27:
    # usage: pmatch string pattern [ pattern ... ]
    function pmatch {
        ${1+typeset x=}"${1-false}" &&
        while command shift; do
            [[ $x == $1 ]] && return
        done 2>/dev/null
        return 1
    }		 [[ -v BASH_VERSION ]] && shopt -s extglob
Line 34: Line 29:
    var='foo bar'
    if pmatch "$var" foo bar baz foo\* blarg; then
        : ...
    fi		 # usage: pmatch string pattern [ pattern ... ]
function any {
    [[ -n $1 ]] || return
    typeset pat match=$1
    shift

    for pat; do
        [[ $match == $pat ]] && return
    done

    return 1
}

var='foo bar'
if any "$var" '@(bar|baz)' foo\* blarg; then
    echo 'var matched at least one of the patterns!'
fi
Line 51: Line 60:
    ${BASH_VERSION+shopt -s extglob}

I want to check if [[ $var == foo || $var == bar || $var == more ]] without repeating $var n times.

The portable solution uses case: 

   # Bourne
   case $var in
      foo|bar|more) ... ;;
   esac

In Bash and ksh, Extended globs can also do this within a [[ command: 

   # bash/ksh
   if [[ $var == @(foo|bar|more) ]]; then
      ...
   fi

Extended globs are turned on by default inside the [[ command in bash 4.1 and newer. If you need to target an older version of bash, you will need to turn them on in your script (shopt -s extglob outside of all functions or compound commands).

Alternatively, you may loop over a list of patterns, checking each individually. 

# bash/ksh93

[[ -v BASH_VERSION ]] && shopt -s extglob

# usage: pmatch string pattern [ pattern ... ]
function any {
    [[ -n $1 ]] || return
    typeset pat match=$1
    shift

    for pat; do
        [[ $match == $pat ]] && return
    done

    return 1
}

var='foo bar'
if any "$var" '@(bar|baz)' foo\* blarg; then
    echo 'var matched at least one of the patterns!'
fi

For logical conjunction (return true if $var matches all patterns), ksh93 can use the & pattern delimiter. 

    # ksh93 only
    [[ $var == @(foo&bar&more) ]] && ...

For shells that support only the ksh88 subset (extglob patterns), you may DeMorganify the logic using the negation sub-pattern operator. 

    # bash/ksh88/etc...
    [[ $var == !(!(foo)|!(bar)|!(more)) ]] && ...

But this is quite unclear and not much shorter than just writing out separate expressions for each pattern.

CategoryShell

BashFAQ/066 (last edited 2022-11-23 19:29:49 by GreyCat)