File name change script not working in second run of loop

Question

This code is meant to search a set of folders containing files with name format DD-MM-YYYY and renames them as YYYY-MM-DD. However, while this loop works fine on the first iteration, it doesn't interpret the regular expression in the second run.

#!/usr/bin/env bash
WORKING_DIRS=( "/directory1" "/directory2" )
for WORKING_DIR in ${WORKING_DIRS[@]}
do
echo "WORKING DIRECTORY : $WORKING_DIR"
echo "--------------------------------------------------------"
for entry in "$WORKING_DIR"/[0-9][0-9]-[0-9][0-9]-[0-9][0-9][0-9][0-9].doc
do
    IFS='/'
    read -r -a array <<< "$entry"
    file_name="${array[${#array[@]}-1]}"
    echo "$file_name"
    IFS='.'
    read -r -a file <<< "$file_name"
    echo "OLD DATE: $file"
    IFS='-'
    read -r -a file_split <<< "${file[0]}"
    day=${file_split[0]}
    month=${file_split[1]}
    year=${file_split[2]}
    new_date="$year-$month-$day"
    echo "NEW DATE : $new_date"
    mv "$WORKING_DIR"/"$file_name" "$WORKING_DIR"/"$new_date".doc
done
done

@Inian Sorry, I upvoted it but didn't have enough rep at the time for it to register. Just upvoted. — N M
– N M, Commented Aug 21, 2017 at 7:43

Inian · Accepted Answer · 2017-08-08 13:17:21Z

The problem is with the IFS value modification in the body of the loop multiple times. Once you modify it the rest of the word-splitting is done by the modified IFS which does not allow your glob pattern to expand.

You can avoid it by passing the value to the read command locally and not modifying it globally, which should solve your problem.

IFS='/' read -r -a array <<< "$entry"
IFS='.' read -r -a file <<< "$file_name"
IFS='-' read -r -a file_split <<< "${file[0]}"

Also in general in looping over a glob pattern it is always to check the file existence before processing the file, to avoid ugly errors

for entry in "$WORKING_DIR"/[0-9][0-9]-[0-9][0-9]-[0-9][0-9][0-9][0-9].doc
do
    [ -e "$entry" ] || continue

    # rest of the code following

(and)

Double-quoting the array expansion as below to avoid getting the individual elements split again. Not doing so, will result in each entry of the array subject to word-splitting by IFS

for WORKING_DIR in "${WORKING_DIRS[@]}"; do

Renaud Pacalet · Accepted Answer · 2017-08-08 06:47:07Z

0

Not sure why your script does not work but without an example content of your directories, it is difficult to reproduce the error. Anyway, it looks a bit complicated for a rather simple task. You could simplify, e.g. by using the =~ operator of the conditional expressions. Example:

for n in "$WORKING_DIR"/*.doc; do
  if [[ $n =~ (.*\/)([0-9][0-9])(-[0-9][0-9]-)([0-9][0-9][0-9][0-9])\.doc ]]; then
    mv $n ${BASH_REMATCH[1]}${BASH_REMATCH[4]}${BASH_REMATCH[3]}${BASH_REMATCH[2]}.doc
  fi
done

edited Aug 8, 2017 at 6:47

answered Aug 8, 2017 at 6:41

Renaud Pacalet

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