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In some of my python-scripts, I got glob.glob(parent_folder_path + glob_str). These lines with the associated files shall be printed out in the console with a proper grep command, but so far I couldn't find out how.

The one which worked for finding all the glob.glob - lines is the following:

grep --exclude-dir='.history' --exclude-dir='__pycache__' --exclude-dir='.wine' -Rinw /home/andylu/Desktop/Python/Scripts/ -e 'glob.glob'

Still it's not the preciseness I would like to achieve. When using 'glob.glob(p*' as the regex-string, only a line with glob.glob() appears in the search result. I couldn't make sense out of this since (p* gave me results with ().

Next, I tried 'glob.glob(p.*' which indeed worked out and showed me all results with glob.glob(parent_folder_path + glob_str).

Even though I managed to find it out via trial and error, I'd like to understand the grep-syntax better. Did the last regex-string work because, according to this cheat-sheet, . stands for any character and * for any number of repeated times?

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  • p*. means zero-or-more occurrences of p character followed by a single character; what pattern do you want to match? answer based on title of the question you only need (p\w+. Commented Dec 21, 2020 at 21:00
  • Sorry, my bad. I actually had 'glob.glob(p.*' working, that's what I wanted to state here, but wrote initially 'glob.glob(p*.'. Thanks for the hint. Your suggestion of (p\w+ did not work though. Commented Dec 21, 2020 at 21:14

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You are very close in your guess. In a regular expression, the sequence p*. means "zero or more of the character p, followed by exactly one of any character":

  • * - Zero or more of the preceding token
  • . - Exactly one character

The more common "global wildcard" in regular expression is .* which means "One or more of any type of character".

Your guess worked because you did not have a $ token (indicating "end of domain") in your expression.

In this case you would probably want the expression /glob\.glob(p.*/:

  • glob\.glob(p - the literal string glob.glob(p, followed by
  • .* - at least one of any type of character

To expound further, if for example you wanted to match more broadly all calls to glob.glob(), you could do something like /glob\.glob\([a-z_+ ]+\)/:

  • glob\.glob\( - the literal string glob.glob(
  • [a-z_+ ]+ - one or more of any of: any letter a-z, an underscore, a +, or a space
  • \) - a literal )
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  • Thanks for the explanation, now I've fully understood why my final approach worked. Nevertheless, I tried out your most elaborate suggestion without a single result returned. Is this due the fact that grep -e doesn't understand certain regex-syntax? The one I tried based in your final suggestion was: grep --exclude-dir='.history' --exclude-dir='__pycache__' --exclude-dir='.wine' -Rinw /home/andylu/Desktop/Python/Scripts/ -e '/glob\.glob\([a-z_+ ]+\)/' --> no result returned Commented Dec 21, 2020 at 21:21
  • Apologies for being unclear- the leading and trailing slashes are a common identifier for "this is a regular expression" (comparable to how quotation marks are a common identifier for "this is an exact quotation") - the actual expression itself does not include them. Commented Dec 21, 2020 at 21:31
  • Okay, now I've removed the quotation marks '..' around your suggested regex, so grep -Rinw /home/andylu/Desktop/Python/Scripts/ -e /glob\.glob\([a-z_+ ]+\)/ results in an error grep: Unmatched [, [^, [:, [., or [=. I don't know how to employ your suggested regex correctly. Commented Dec 21, 2020 at 21:39
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    When I simply run grep -E 'glob\.glob\([a-z_+ ]+\)' foo.py on an test file, it works perfectly. In your case, try replacing the -e with -Ee to use an Extended Regular Expression, which I believe we need because of the + token. Commented Dec 21, 2020 at 21:44
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    Finally, that was it: we need both e-flags Ee to make it work, put the regex into quotes and remove the leading and trailing slashes. The working result is: grep /home/andylu/Desktop/Python/Scripts/ -Ee 'glob\.glob\([a-z_+ ]+\)' Commented Dec 21, 2020 at 21:48

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