problem with passing argument to -exec in find command

[secondmouse]

Hi all, I'm writing a script to preserve the creation dates of the files to be converted to other formats. For the names of the converted files, I believe these are the most common patterns, for example,

• *.doc -> *.txt

• *.doc - > *.doc.txt

and I came up with this bash script

#!/bin/bash
# script name: fixdate
usage() {
  echo "usage: `basename $0` src_path src_ext dest_path dest_ext [append|replace]"
}
MODE="replace"

case $# in
  5|4)
    [ $# -eq 5 ] && MODE=$5
    case $MODE in
      append)
        find $1 -name "*.$2" -exec touch -c -r {} $3/`basename {}`.$4 \;
        ;;
      replace)
        find $1 -name "*.$2" -exec touch -c -r {} $3/`basename {} $2`$4 \;
        ;;
      *)
        usage
        ;;
    esac
    ;;
  *)
    usage
    ;;
esac

It works only in the append mode. For example, if I do a

fixdate . doc . txt append

, it works as expected, that is, creation dates of ./*.txt got replaced with those of ./*.txt.doc
But when I try to run

fixdate . doc . txt replace

, or

fixdate . doc . txt

, the creation dates of ./*.txt don't get replaced by those of ./*.doc
I can work around this by changing the bold line in the script into

 find $1 -name "*.$2" | while read F; do touch -c -r $F $3/`basename $F $2`$4; done

I kind of know that $2 in the original code didn't get passed into `basename` in -exec under replace mode but I don't know exactly why and I hope someone could point out what the problem is. Thank you.

[burschik]

Shouldn't that be

find $1 -name "*.$2" -exec touch -c -r {} $3/`basename {}`$2 $4 \;

[secondmouse]

Shouldn't that be

find $1 -name "*.$2" -exec touch -c -r {} $3/`basename {}`$2 $4 \;

No it doesn't work this way.

[burschik]

Right. I'm afraid that won't work, as the "{}" has not yet been replaced by the filename found when you call basename. It might be a better idea to generate a list of matching filenames and then feed it to touch via a loop, e.g.

find -name whatever | while read filename;
    do manipulate filename;
    touch -cr oldname newname; 
done

[secondmouse]

My final version of this script:

#!/bin/bash
# script to change converted files' creation dates
# usage:
#   fixdate src_path src_ext dest_path dest_ext [append|replace]
usage() {
  echo "usage:"
  echo "        `basename $0` src_path src_ext dest_path dest_ext [append|replace]"
  echo "        by default, replace mode will be used, that is, for example, converted files are in *.txt format while the origins are *.doc format"
  echo "        alternatively, append mode can be specified if the converted files are in *.doc.txt format"
  echo "example:"
  echo "        `basename $0` . doc converted/ txt"
  echo "        set the dates of *.txt under converted/ to be the same as those of ./*.doc"
  echo "note:"
  echo "        filenames/paths in this script are case sensitive"
}

MODE="replace"

case $# in
  5|4)
    [ $# -eq 5 ] && MODE=$5
    case $MODE in
      append)
        find $1 -name "*.$2" -type f | while read F; do dest_name=$3/`basename "$F"`.$4; touch -c -r "$F" "${dest_name}"; done
        ;;
      replace)
        find $1 -name "*.$2" -type f | while read F; do dest_name=$3/`basename "$F" $2`$4; touch -c -r "$F" "${dest_name}"; done
        ;;
      *)
        usage
        ;;
    esac
    ;;
  *)
    usage
    ;;
esac

This improved version takes care of the argument passing problem, also the modifications apply to only files, whose names might contain space(s).