while [ "$(ls -l --full-time TargetFile)" != "$a" ] ; do a=$(ls -l --full-time TargetFile); sleep 10; done

Wait for file to stop changing

Here's a way to wait for a file (a download, a logfile, etc) to stop changing, then do something. As written it will just return to the prompt, but you could add a "; echo DONE" or whatever at the end. This just compares the full output of "ls" every 10 seconds, and keeps going as long as that output has changed since the last interval. If the file is being appended to, the size will change, and if it's being modified without growing, the timestamp from the "--full-time" option will have changed. The output of just "ls -l" isn't sufficient since by default it doesn't show seconds, just minutes. Waiting for a file to stop changing is not a very elegant or reliable way to measure that some process is finished - if you know the process ID there are much better ways. This method will also give a false positive if the changes to the target file are delayed longer than the sleep interval for any reason (network timeouts, etc). But sometimes the process that is writing the file doesn't exit, rather it continues on doing something else, so this approach can be useful if you understand its limitations.

2 Alternatives + Submit Alt

  • This loop will finish if a file hasn't changed in the last 10 seconds. . It checks the file's modification timestamp against the clock. If 10 seconds have elapsed without any change to the file, then the loop ends. . This script will give a false positive if there's a 10 second delay between updates, e.g. due to network congestion . How does it work? 'date +%s' gives the current time in seconds 'stat -c %Y' gives the file's last modification time in seconds '$(( ))' is bash's way of doing maths '[ X -lt 10 ]' tests the result is Less Than 10 otherwise sleep for 1 second and repeat . Note: Clever as this script is, inotify is smarter. Show Sample Output


    3
    while [ $(( $(date +%s) - $(stat -c %Y FILENAME) )) -lt 10 ]; do sleep 1; done; echo DONE
    flatcap · 2015-05-09 12:30:13 0
  • perl version of "Wait for file to stop changing" When "FileName" has not been changed for last 10 seconds, then print "DONE" "10" in "(stat)[10]" means ctime. One have other options like atime, mtime and others. http://perldoc.perl.org/functions/stat.html


    0
    echo FileName | perl -nlE'sleep 1 while time-(stat)[10]<10' && echo DONE
    pung96 · 2015-05-09 14:58:41 0

What Others Think

"inotifywait -e IN_CLOSE_WRITE" is likely a cleaner/better approach.
dmmst19 · 83 weeks and 6 days ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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