Check whether a certain file type/extension exists in directory

Question

How would you go about telling whether files of a specific extension are present in a directory, with bash?

Something like

if [ -e *.flac ]; then 
echo t         


        

Answer 1

   shopt -s nullglob
   set -- $(echo *.ext)
    if [ "${#}" -gt 0 ];then
      echo "got file"
    fi

Answer 2

This uses ls(1), if no flac files exist, ls reports error and the script exits; othewise the script continues and the files may be be processed

#! /bin/sh
ls *.flac  >/dev/null || exit
## Do something with flac files here

Answer 3

Here is a solution using no external commands (i.e. no ls), but a shell function instead. Tested in bash:

shopt -s nullglob
function have_any() {
    [ $# -gt 0 ]
}

if have_any ./*.flac; then
    echo true
fi

The function have_any uses $# to count its arguments, and [ $# -gt 0 ] then tests whether there is at least one argument. The use of ./*.flac instead of just *.flac in the call to have_any is to avoid problems caused by files with names like --help.

Answer 4

You can use -f to check whether files of a specific type exist:

#!/bin/bash

if [ -f *.flac ] ; then
   echo true
fi 

Answer 5

bash only:

any_with_ext () ( 
    ext="$1"
    any=false
    shopt -s nullglob
    for f in *."$ext"; do
        any=true
        break
    done
    echo $any 
)

if $( any_with_ext flac ); then
    echo "have some flac"
else 
    echo "dir is flac-free"
fi

I use parentheses instead of braces to ensure a subshell is used (don't want to clobber your current nullglob setting).

Answer 6

You need to be carful which flag you throw into your if statement, and how it relates to the outcome you want.

If you want to check for only regular files and not other types of file system entries then you'll want to change your code skeleton to:

if [ -f file ]; then
echo true;
fi

The use of the -f restricts the if to regular files, whereas -e is more expansive and will match all types of filesystem entries. There are of course other options like -d for directories, etc. See http://tldp.org/LDP/abs/html/fto.html for a good listing.

As pointed out by @msw, test (i.e. [) will choke if you try and feed it more than one argument. This might happen in your case if the glob for *.flac returned more than one file. In that case try wrapping your if test in a loop like:

for file in ./*.pdf
do
    if [ -f "${file}" ]; then
    echo 'true';
    break
    fi
done

This way you break on the first instance of the file extension you want and can keep on going with the rest of the script.