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up vote 4 down vote favorite

I was using this little script to find malformed images:

find -name '*.jpg' -exec identify -format "%f\n" {} \; 2>errors.txt

It worked well enough, but now I need to modify it slightly. Instead of dumping the stderr to errors.txt, I want to dump the filename (%f) of the image that triggered the error. That is, I want a list of the malformed image files in errors.txt instead of a list error messages.

I tried adding || echo "%f" >> errors.txt to the -exec portion, but that didn't work. What would be the best way to do this?

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3 Answers 3

up vote 3 down vote accepted

This finds malformed images and stores their names in names.txt:

find -name '*.jpg' -exec bash -c 'identify "$1" &>/dev/null || echo "$1">>names.txt' none {} \;

How it works

  • find -name '*.jpg'

    This starts up find as usual.

  • -exec bash -c 'identify "$1" &>/dev/null || echo "$1" >names.txt' none {} \;

    This runs identify on each file and, if identify returns a non-zero error code, it echoes the file name to names.txt.

    bash -c '...' none {} causes a bash shell to run the command in the quotes with the file name in {} assigned to positional argument $1.

    For the curious, the string none is assigned to $0. Since we never use $0, the none is, in effect, a dummy placeholder.

Discussion

I tried adding || echo "%f" >> errors.txt to the -exec portion, but that didn't work. What would be the best way to do this?

The subtlety is that the || has to operate on the identify command. To that, we need to put identify in a shell such as by using bash -c as shown above.

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Works great, and thanks for the explanation -- the 'bash' addition makes perfect sense. One minor thing: I had to change >names.txt to >>names.txt in order to get a list. –  Phll Apr 11 at 23:15
    
@Phll Glad it worked for you. Sorry about the > thing: the answer is now corrected. –  John1024 Apr 12 at 1:08
up vote 0 down vote

So you want like...

find . -name '*.jpg'  \
       ! -exec identify -silent {} \; \
       -print 2>/dev/null >errors.txt
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up vote 1 down vote 
find . -name '*.jpg' -exec sh -c '
  for file do
    if identify "$file"; then
      printf "%s\n" "$file" >&3
    else
      printf "%s\n" "$file" >&4
    fi
  done' sh {} + 3> good 4> bad > /dev/null 2>&1
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