How to drop final portion of multiple directory names?

Question

I have a number of directories with titles such as "20150512_101129_3016" and others with additional string following an additional underscore, such as "20150512_101129_3016_v1A" (it's not always v1A, could be v1, or V1a, etc). I would like to rename all directories such that the final string following the final underscore is removed. I'd prefer a solution that looks to remove all text following (and including) the final/3rd underscore since I am uncertain that all directory names will have the same number of characters in the text preceding the 3rd underscore.

Answer 1

You can do this with a simple shell loop:

for x in ./*_*_*_*; do mv -i "$x" "${x%_*}"; done

i.e. for every file whose name contains at least three underscores, rename the file, stripping off the part starting at the last underscore.

If there's a collision (e.g. both 20150512_101129_3016_v1A and 20150512_101129_3016_v1B exist), then the first file in lexicographic order is renamed to the desired target, and the second one is moved to a subdirectory, i.e. 20150512_101129_3016_v1B gets moved to 20150512_101129_3016/20150512_101129_3016_v1B after 20150512_101129_3016_v1A has been renamed to 20150512_101129_3016. To avoid this, add an extra check:

for x in ./*_*_*_*; do
  if [ -e "${x%_*}" ]; then
    echo "Not renaming $x because ${x%_*} already exists"
    continue
  fi
  mv "$x" "${x%_*}"
done

Alternatively, on Linux, pass the -T option to mv to make it do this check.

Answer 2

if the original directory names are homogeneous, i.e. follows the format of XXXXX_XXXX_XXXX (then may be followed by another _ XXXX) this code segment below, should work:

find ./ -maxdepth 1 -type d | while read dir; do
newdir=$(echo ${dir} | cut -d_ -f1-3)
# duplicate directory name protection
if [ -d ${newdir} ]
then 
  newdir=${newdir}_
  echo "duplicate directory encountered. Appending _ to the new dir name"
fi

#did the dir name change ? If not, do nothing
if [ ${newdir} != ${dir} ]
then
  mv ${dir} ${newdir}
fi
done

it assumes you are in the directory which contains these subdirectories.