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Top Forums Shell Programming and Scripting How to find out whether a file exists with the help of regular expression? Post 302705167 by alister on Monday 24th of September 2012 10:56:13 AM
Old 09-24-2012
Quote:
Originally Posted by radoulov
You didn't specify which shell you're using.
With most modern Bourne type shells (zsh, bash, ksh93) you could do something like this:

Code:
_files=( *EQST* )
(( ${#_files[@]} )) && echo 'file(s) exist'

Generally, that won't work either. If the pattern goes unmatched, it remains unmodified and will be assigned to the array as is. If there is no match, the array will have 1 member. If one file matches, the array will also have 1 member. If many files match, the array will have more than 1 member. In all cases, the subsequent test will evaluate to true.

Some shells can be told to replace unmatched patterns with a null string (e.g. bash's shopt -s nullglob), but this is not the default, standard-compliant behavior.

Regards,
Alister
 

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REGEX(3)						     Library Functions Manual							  REGEX(3)

NAME
re_comp, re_exec - regular expression handler SYNOPSIS
char *re_comp(s) char *s; re_exec(s) char *s; DESCRIPTION
Re_comp compiles a string into an internal form suitable for pattern matching. Re_exec checks the argument string against the last string passed to re_comp. Re_comp returns 0 if the string s was compiled successfully; otherwise a string containing an error message is returned. If re_comp is passed 0 or a null string, it returns without changing the currently compiled regular expression. Re_exec returns 1 if the string s matches the last compiled regular expression, 0 if the string s failed to match the last compiled regular expression, and -1 if the compiled regular expression was invalid (indicating an internal error). The strings passed to both re_comp and re_exec may have trailing or embedded newline characters; they are terminated by nulls. The regular expressions recognized are described in the manual entry for ed(1), given the above difference. SEE ALSO
ed(1), ex(1), egrep(1), fgrep(1), grep(1) DIAGNOSTICS
Re_exec returns -1 for an internal error. Re_comp returns one of the following strings if an error occurs: No previous regular expression, Regular expression too long, unmatched (, missing ], too many () pairs, unmatched ). 3rd Berkeley Distribution May 15, 1985 REGEX(3)
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