Function that outputs dots every second until command completes

sleeper(){ while `ps -p $1 &>/dev/null`; do echo -n "${2:-.}"; sleep ${3:-1}; done; }; export -f sleeper
Very useful in shell scripts because you can run a task nicely in the background using job-control and output progress until it completes. Here's an example of how I use it in backup scripts to run gpg in the background to encrypt an archive file (which I create in this same way). $! is the process ID of the last run command, which is saved here as the variable PI, then sleeper is called with the process id of the gpg task (PI), and sleeper is also specified to output : instead of the default . every 3 seconds instead of the default 1. So a shorter version would be sleeper $!; The wait is also used here, though it may not be needed on your system. echo ">>> ENCRYPTING SQL BACKUP" gpg --output archive.tgz.asc --encrypt archive.tgz 1>/dev/null & PI=$!; sleeper $PI ":" 3; wait $PI && rm archive.tgz &>/dev/null Previously to get around the $! not always being available, I would instead check for the existance of the process ID by checking if the directory /proc/$PID existed, but not everyone uses proc anymore. That version is currently the one at http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html but I plan on upgrading to this new version soon.
Sample Output
>>> ENCRYPTING SQL BACKUP

::::::::::::::::::

  DONE


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What Others Think

You might want to run `shred -u' on the backup after it's encrypted so it's not possible to examine the disk contents and retrieve it. (But that depends on how paranoid you are.)
h3xx · 360 weeks and 4 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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