Extended Regular Expression in UNIX

NickName:Mahmoud Emam Ask DateTime:2013-04-14T22:23:12

Extended Regular Expression in UNIX

I don't mean that this question for UNIX only, but I work on Solaris, and I didn't try it on any other OS. I confused between the extended regular expression:

first:

[[ "str" == ?(str|STR) ]] && echo "matched"

this work correct, but when:

[[ "str str" == ?(str|STR)(.*) ]] && echo "matched"

it doesn't work, does it mean that I can only compare one pattern.

Second:

[[ "str" =~ ?(str|STR) ]] && echo "matched"

I can't use this form here why?, but when:

[[ "str" == (str|STR)? ]] && echo "matched"

it works correctly.

Copyright Notice：Content Author:「Mahmoud Emam」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/16000097/extended-regular-expression-in-unix

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