How can I test for the .RAW file extension?

Question

I'm trying to set up an sh script that will run every 30 minutes. During each run, I want to check a directory for the presence of at least one .RAW file. Upon finding that file extension, I will have other code to execute, but right now I'm having trouble figuring out the correct if statement to use.

I know this code example isn't the most ideal way to do it, but here's the code I tried which is obviously wrong:

cd ./dir/
if [ ! -f "*.RAW"]; then
  echo "No files!"
else
  echo "Yes files!"
fi

How can I correctly test for the presence of the .RAW extension?

Answer 1

With zsh:

files=(*.RAW(DN))
if (($#files)); then
  echo Yes
else
  echo No
fi

If you're only interested in regular files (or symlinks to regular files) as your -f implies, that would be:

file=(*.RAW(ND-.))

instead.

POSIXly:

has_regfiles_by_extension() {
  for ext do
    for file in .*."$ext" ."$ext" *."$ext"; do
      [ -f "$file" ] && return
    done
    return 1
  done
}

if has_regfiles_by_extension RAW raw; then
  echo YES
else
  echo NO
fi

If you wanted to use ls instead, you could do:

if ls -Aq | grep -q '\.RAW$'; then
  echo yes
else
  echo no
fi

One of the benefits is that if the directory is not readable, you'll get an error message (instead of being silently ignored in the case of shell globs).

Answer 2

Your example answer is almost correct. First, you need to separate the testing string ".RAW" from the closing ]:

if [ ! -f "*.RAW" ];

You can do shell globbing in this context by taking the asterisk outside of the quotes. So the finished command would be:

if [ ! -f *".RAW" ];

---

However, this approach isn't so useful if you want to use the .RAW files. If that's the case, I'd compare the extension of each file in the directory like so:

for file in "test/"*; do
    if [ "${file##*.}" = "RAW" ]; then
        echo "Found raw file"
    fi
done

The Bash syntax ${var##*.} is a part of the clever shell parameter expansion you can do. You can find more information on the GNU website.

Answer 3

Thanks for all the help, although I haven't been able to get some of these to work.

I did, however, successfully implement code I found in an answer to another question! (https://unix.stackexchange.com/a/87476)

export DIR=./folder
if ls ${DIR}/*.RAW &>/dev/null
then
  echo "Yes!"
else
  echo "No!"
fi

Answer 4

Two Bourne Shell Solutions

With the Bourne shell (which doesn't support arrays, or shell options like nullglob or failglob) you have to work around the fact that a non-zero exit status or the glob itself will be returned if a glob isn't found. For example:

if [ -n "`ls *.RAW 2> /dev/null`" ]; then
    echo "At least one RAW file found!"
else
    echo "No RAW files found."
fi

In general, one shouldn't rely on the output of the ls command, but this is sufficient for your use case and works around the limitations of the Bourne shell. If you really want to use only shell built-ins, you have to use assignment and explicitly test for the glob itself as an error condition. For example:

files=*.RAW
if [ "$files" = "*.RAW" ]; then
    echo "No RAW files found."
else
    echo "At least one RAW file found!"
fi