Pipe results of grep into find

Question

I have a logfile with some filenames inbetween other events, which I need to find in subfolders. Same necessity for filenames inside xml files which has to be found inside some folder and subfolders. Looks to me I should use grep on the logfile and extract exact filenames, feed those to find. I can easily get a list of filenames one per line, but getting it to work with find is not exactly working. And internet is full with answers for other way around - find results feeding into grep.

grep -oP '(?<=Some problem with file named ).*pdf(?=\.)' /home/myname/log/myspecificlogfile.log

I tried piping results of this command to xargs and find, but it doesnt give any results both on files not actually there and ones there. Echo is just to simplify, find parameter -ls is not yet added (but I will need it):

echo 12345.pdf | xargs -0 -I{} find /home/myname/workfolders/ -name '{}'    #Nonexisting pdf
echo 67890.pdf | xargs -0 -I{} find /home/myname/workfolders/ -name '{}'   #Existing pdf, no results

How do I get grep results piped to find to find my files in a folder and eventually subfolders?

Answer 1

I'd do:

grep -oP '(?<=Some problem with file named ).*pdf(?=\.)' \
  /home/myname/log/myspecificlogfile.log | awk -F / '
     ARGIND == 1 {files[$0]; next}
     $NF in files' - RS='\0' <(
     find /home/myname/workfolders/ -name '*pdf' -type f -print0)

(assumes the GNU implementation of grep and awk and a shell with support for process substitution like ksh, zsh or bash).

Using find's -name would not be ideal for files names *.pdf or ?.pdf for instance. Running one find per file name would be inefficient. Even if you made a solution that calls one find with -name a.pdf -o -name b.pdf... that would probably still be less efficient than a hash lookup as done by awk.

Answer 2

Other variant to use find + grep

find /home/myname/workfolders/ \
     -name '*pdf' -type f -exec grep -qFf \
          <(grep -oP '(?<=Some problem with file named ).*pdf?(?=\.)'\
                 /home/myname/log/myspecificlogfile.log) \
     -print

Or you can divide it in two command with pipe

find /home/myname/workfolders/ -name '*pdf' -type f |
grep -qFf <(grep -oP '(?<=Some problem with file named ).*pdf?(?=\.)' \
            /home/myname/log/myspecificlogfile.log)