How to find out whether a file exists with the help of regular expression?

Shell Programming and Scripting
1

Hi all
I have a list of file names in array. But this file names are not exact. so i want to search whether a file exists or not using regular expression.
code snippet:

if [ -f "*EQST*" ];
then
echo "File exists"
else
echo "File does not exits"
fi

over here "*EQST*" should be treated as a regular expression. and the Actual file name in the directory will be something like 'Exp_BK_FT_T_EQST.txt'.

So how should i do this?
The above could is taking *EQST* as a string and trying to search with the same name.

TIA
Regards
Ganesh

---------- Post updated at 02:51 PM ---------- Previous update was at 02:45 PM ----------

Hey got it no need to reply. i just had to remove the double quotes from the if clause.

Thanks & Sorry
Ganesh

2

You didn't specify which shell you're using.
With most modern Bourne type shells (zsh, bash, ksh93) you could do something like this:

_files=( *EQST* )
(( ${#_files[@]} )) && echo 'file(s) exist'
3

That won't work if more than one file matches the pattern.

4

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

5

Absolutely right, Alister!
Thanks for pointing this out!

For zsh: setopt nullglob or your_pattern(N) .
For ksh93: ~(N)your_pattern .

In some cases dotglob could also be desirable.

If none of the above shells is available:

for f in *EQST*; do
  if [ -e "$f" ]; then 
    echo exist  
    break
  fi
done