CODEWITHSUNDEEP
linuxbashshellunix
hshantanu
hshantanu

Reputation: 454

Cut and remove a string from another string in shell script

I have a following string in a shell script.

var="rule:access=allow,default=default value,OTHER=0,SOMETHING=1"

I need to remove "default=default value" from $var. Thus, the final string will become as follows:

var="rule:access=allow,OTHER=0,SOMETHING=1"

NOTE: The value after default may be anything. It could be "default=something else". It is not fixed. I need to remove that text. How can this be done?

Upvotes: 1

Views: 5414

Answers (3)

beroe
beroe

Reputation: 12316

You can use two parameter expansions, one to get the stuff after the comma of default=* and one to get the part before default....

var="rule:access=allow,default=default value,OTHER=0,SOMETHING=1"

endo=${var#*default}
echo ${var/default=*}${endo#*,}

rule:access=allow,OTHER=0,SOMETHING=1

But sed might be easier...!

Upvotes: 0

John1024
John1024

Reputation: 113814

Answer for revised question

$ echo "$var" | sed 's/default=[^,]*,//'
rule:access=allow,OTHER=0,SOMETHING=1

If we want to update the value of var, we use command substitution:

$ var="$(echo "$var" | sed 's/default=[^,]*,//')"
$ echo "$var"
rule:access=allow,OTHER=0,SOMETHING=1

Answer for original question

Using bash

To remove default=default value,, use pattern substitution:

$ var="${var/default=default value,/}"
$ echo "$var"
rule:access=allow,OTHER=0,SOMETHING=1

This feature is documented in man bash:

${parameter/pattern/string}
Pattern substitution. The pattern is expanded to produce a pattern just as in pathname expansion. Parameter is expanded and the longest match of pattern against its value is replaced with string. If pattern begins with /, all matches of pattern are replaced with string. Normally only the first match is replaced. If pattern begins with #, it must match at the beginning of the expanded value of parameter. If pattern begins with %, it must match at the end of the expanded value of parameter. If string is null, matches of pattern are deleted and the / following pattern may be omitted. If parameter is @ or *, the substitution operation is applied to each positional parameter in turn, and the expansion is the resultant list. If parameter is an array variable subscripted with @ or *, the substitution operation is applied to each member of the array in turn, and the expansion is the resultant list.

Using sed

$ var="$(echo "$var" | sed 's/default=default value,//')"
$ echo "$var" 
rule:access=allow,OTHER=0,SOMETHING=1

Upvotes: 3

Utsav
Utsav

Reputation: 8093

Assign this to var again.

echo $var|sed 's/default=default value//'|sed 's/,,/,/'

Last sed to take care of scenarios where default=default value is the first or last keyword in string.

Upvotes: 0

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