CODEWITHSUNDEEP
linuxbashshelldatestring-formatting
Jim
Jim

Reputation: 875

Preserve timestamp when editing file

I want to preserve the timestamp of the files I'm editing in a for loop

for files in $DIR/MDC*/$FILE
do
    # Need to get date here!
    dos2unix $files
    if grep -q $TYPE $files; then
        echo 'done'
    else
        sed -i "1s/^/$TYPE\n/" $files
    fi
    $DIR/crccalc/LDDR16.py $files
    # Use Date variable here to change it back

done

The issue is I need to get a formatted date string from the file so that I can do touch -r to revert the files date back once the loop has completed.

stat is not giving the me the format I need.

Required Format:

YYMMDDhhmm

Upvotes: 1

Views: 1875

Answers (2)

Burcardo
Burcardo

Reputation: 111

Another attempt that can be run straight from the terminal.

FIRST do step one, then start working with your files.

  1. Preserve old timestamps. It operates from the current directory, excludes all hidden files, and saves it to the temporary file in /tmp/files. You can always change parameters, but better stay with -printf '"%t" "%p"\n' since the later touch command utilizes that.

    find . ! -iname ".*" -printf '"%t" "%p"\n' -type f > /tmp/files

  2. Modify your files as much as you like

  3. now create a file that helps you restoring the timestamps:

    while read line; do echo touch -a -d $line >> job.sh; done < /tmp/times

  4. And finally apply the old dates to the modified files

    sh job.sh

Caveat: works for files with name spacing, special characters, but for instance no files with a $ sign and ones with a double space in it.

Upvotes: 1

fedorqui
fedorqui

Reputation: 289555

There is a nice trick for this: using touch -r reference_file. That is, touch the file using the timestamp of another file as a reference.

From man touch:

   -r, --reference=FILE
          use this file's times instead of current time

And you may be asking: and how can this help you? Well, because you can create a dummy file dummy to work with:

  • Before modifying a file you touch the dummy with the timestamp of the file original_file you want to modify.
  • You modify the original_file.
  • Then you touch the original_file using the timestamp of the dummy one.

All together:

for files in $DIR/MDC*/$FILE
do
    # copy its timestamp to `dummy_file`
    touch -r "$files" "dummy_file"

    # ...things...

    # Use Date variable here to change it back
    touch -r "dummy_file" "$files"
done

Upvotes: 6

Related Questions