Basic UNIX regular expression in python

Question

I'm trying to use the re.match() method to check if my string looks like the regular expression.

In UNIX on the cmd line I'd use "*,*" to check against a string such as, hello,there.

The following python doesn't work, what is there to change?

# line is just some string
if re.match(r'*,*', line):
    # do something

The key here is that regular expressions are not the same as shell globs. The shell glob *,* would be .*,.* as a regex. — Andy Lester
– Andy Lester, Commented Oct 15 at 17:14

Charles Duffy · Accepted Answer · 2018-08-17 16:39:37Z

2

*,* on UNIX is not a regular expression. In regex, * means to take 0 or more of the preceding character. If you want to check if there is a comma between strings, you can do:

if re.match(r"\w+,\w+"):
    pass

\w specifies a word character, and + specifies one or more. So you are saying I want a comma, between two words.

edited Aug 17, 2018 at 16:39

Charles Duffy

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answered Aug 17, 2018 at 16:38

Kusti8

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2 Comments

Charles Duffy Over a year ago

Another option would be to point the OP at the fnmatch standard-library Python module, which does implement standard UNIX shell pattern matching.

Simone-Cu Oct 15 at 10:11

As a side note, those are called wildcards or globbing patterns. As said, those are note really regular expressions. You may want to look at tldp.org/LDP/GNU-Linux-Tools-Summary/html/x11655.htm

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