CODEWITHSUNDEEP
regexlinuxbash
Srinivasarao Kotipatruni
Srinivasarao Kotipatruni

Reputation: 315

Issue with RegEx in matching timestamp in filename in Linux bash

I have the following code written to check if my filename ends with some format like given below. It is working when tested online at https://regex101.com/ but not in linux bash. Please help me find out the issue.

Ex: timestamp_foramt="^[\s\S]+_INFT_[0-9]{8}_[0-9]{6}[.][\w]+$" FNAME="Payments.test_INFT_20191218_075918.txt" #example if [[ ! $FNAME =~ $timestamp_foramt ]]; then echo non-format; else echo format; fi non-format

Please help me understand why it is not working in bash. Did I commit something wrong in regex for timestamp_foramt?

Upvotes: 2

Views: 162

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626690

You can fix the current expression like this:

timestamp_foramt="^.+_INFT_[0-9]{8}_[0-9]{6}\.[[:alnum:]_]+$"
FNAME="Payments.test_INFT_20191218_075918.txt" #example
if [[ ! $FNAME =~ $timestamp_foramt ]]; then
  echo 'non-format';
else
  echo 'format';
fi;

See the online Bash demo.

Main points:

  • [\s\S] can be used in Perl and other NFA regex engines to match any character, in POSIX ERE, used in Bash, you may simply use a .
  • \w is better written as [[:alnum:]_] in POSIX ERE as it is more portable to match letters, digits and underscores.

Upvotes: 3

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