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edited Mar 30, 2015 at 5:10

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Here is one way (put it in a file and execute it with any POSIX shell like bash or ksh):

cd ~/somefolder/ || exit 1 for f in *.png do case $f in (tn_*) continue ;; (*) convert "${f}" -resize 50%x50% "tn_${f}" ;; esac done

With modern shells the case construct could also be replaced by a terser conditional command:

cd ~/somefolder/ || exit 1 for f in *.png do [[ "$f" != tn_* ]] && convert "${f}" -resize 50%x50% "tn_${f}" done

(But this code is from memory and untested, so inspect the convert command about the actual resize-syntax, and try it in some sample directory on a few sample files first.)

Here is one way (put it in a file and execute it with any POSIX shell like bash or ksh):

cd ~/somefolder/ || exit 1 for f in *.png do case $f in (tn_*) continue ;; (*) convert "${f}" -resize 50%x50% "tn_${f}" ;; esac done

(But this code is from memory and untested, so inspect the convert command about the actual resize-syntax, and try it in some sample directory on a few sample files first.)

Here is one way (put it in a file and execute it with any POSIX shell like bash or ksh):

cd ~/somefolder/ || exit 1 for f in *.png do case $f in (tn_*) continue ;; (*) convert "${f}" -resize 50%x50% "tn_${f}" ;; esac done

With modern shells the case construct could also be replaced by a terser conditional command:

cd ~/somefolder/ || exit 1 for f in *.png do [[ "$f" != tn_* ]] && convert "${f}" -resize 50%x50% "tn_${f}" done

(But this code is from memory and untested, so inspect the convert command about the actual resize-syntax, and try it in some sample directory on a few sample files first.)

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answered Mar 30, 2015 at 4:48

Janis

14.4k
4
28
42

Here is one way (put it in a file and execute it with any POSIX shell like bash or ksh):

cd ~/somefolder/ || exit 1 for f in *.png do case $f in (tn_*) continue ;; (*) convert "${f}" -resize 50%x50% "tn_${f}" ;; esac done

(But this code is from memory and untested, so inspect the convert command about the actual resize-syntax, and try it in some sample directory on a few sample files first.)