replace
Unlike Bourne Again Shell (bash), POSIX shell does not have a native find/replace function for replacing one occurrence of a pattern in a given string with another. Below is an implementation written in native POSIX shell that is:
Faster than piping to
awk
,sed
,perl
,python
,ruby
, or other langaugeCompatible with
bash
and all other POSIX-compliant shellsOptimized to use
${parameter/pattern[/string]}
whenbash
is detected
1 #!/bin/sh
2 if [ "$BASH_VERSION" ]; then
3 replace() # $var_to_get $find $replace [$var_to_set]
4 {
5 eval ${4:-$1}=\"\${$1/\$2${3:+/\$3}}\"
6 }
7 else
8 # NB: On FreeBSD, sh(1) runs this faster than bash(1) runs the above
9 replace() # $var_to_get $find $replace [$var_to_set]
10 {
11 eval local __left= __right=\"\$$1\" || return
12 case "$__right" in *$2*)
13 __left="${__right%%$2*}$3"
14 __right="${__right#*$2}"
15 esac
16 eval ${4:-$1}=\"\$__left\$__right\"
17 }
18 fi
19 eval echo \"before=[\$$1]\"
20 replace "$@"
21 eval echo \" after=[\$${4:-$1}]\"
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