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How can I include the regex match in the replacement expression in BASH?
Non-working example:
#!/bin/bash
name=joshua
echo ${name//[oa]/X\1}
I expect to output jXoshuXa with \1 being replaced by the matched character.
This doesn't actually work though and outputs jX1shuX1 instead.
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A regular expression matching sign, the =~ operator, is used to identify regular expressions. Perl has a similar operator for regular expression corresponding, which stimulated this operator. Let's have some examples to see the working of =~ operator in Ubuntu 20.04.
You can use the test construct, [[ ]] , along with the regular expression match operator, =~ , to check if a string matches a regex pattern (documentation). where commands after && are executed if the test is successful, and commands after || are executed if the test is unsuccessful.
The 'sed' command is used to replace any string in a file using a bash script. This command can be used in various ways to replace the content of a file in bash. The 'awk' command can also be used to replace the string in a file.
$BASH_REMATCH is an array and contains the matched text snippets. ${BASH_REMATCH[0]} contains the complete match. The remaining elements, e.g. ${BASH_REMATCH[1]} , contain the portion which were matched by () subexpressions.
The question bash string substitution: reference matched subexpressions was marked a duplicate of this one, in spite of the requirement that
The code runs in a long loop, it should be a one-liner that does not launch sub-processes.
So the answer is:
If you really cannot afford launching sed in a subprocess, do not use bash ! Use perl instead, its read-update-output loop will be several times faster, and the difference in syntax is small. (Well, you must not forget semicolons.)
I switched to perl, and there was only one gotcha: Unicode support was not available on one of the computers, I had to reinstall packages.
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