replaceall

Unlike Bourne Again Shell (bash), POSIX shell does not have a native find/replace function for replacing all occurrences 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 langauge
Compatible with bash and all other POSIX-compliant shells
Optimized to use ${parameter//pattern[/string]} when bash is detected
1
 1 #!/bin/sh
2
 2 if [ "$BASH_VERSION" ]; then
3
 3     replaceall() # $var_to_get $find $replace [$var_to_set]
4
 4     {
5
 5         eval ${4:-$1}=\"\${$1//\$2${3:+/\$3}}\"
6
 6     }
7
 7 else
8
 8     # NB: On FreeBSD, sh(1) runs this faster than bash(1) runs the above
9
 9     replaceall() # $var_to_get $find $replace [$var_to_set]
10
10     {
11
11         eval local __left= __right=\"\$1\" || return
12
12         while :; do
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13             case "$__right" in *$2*)
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14                 __left="$__left${__right%%$2*}$3"
15
15                 __right="${__right#*$2}"
16
16                 continue
17
17             esac
18
18             break
19
19         done
20
20         __left="$__left${__right#*$2}"
21
21         eval ${4:-$1}=\"\$__left\"
22
22     }
23
23 fi
24
24 eval echo \"before=[\$1]\"
25
25 replaceall "[email protected]"
26
26 eval echo \" after=[\${4:-$1}]\"
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