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Mayeu
Mayeu

Posted on • Originally published at mayeu.me

How to run a command in your shell until it succeed

I am regularly copying big files over the internet via rsync, and since I am travelling a lot, I don't generally have access to stable internet connection, so I end-up rerunning the command multiple times until it succeeds.

Turns out there is a better way. Of course you could use while and test the return of the command, but that sounds like a lot of work for a ad hoc command. But I am lazy and I recently discovered that an until command exists!

Pretty straightforward to use:

$ until <put your command here>; do echo "Retrying at `date -Iminutes`"; done
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So with rsync you get:

$ until rsync -aP src:/path/to/src dest/; do echo "Retrying at `date -Iminutes`"; done
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And if you are really lazy, just create an alias (left as an exercise ;) ).

This post was originally published on mayeu.me.

Discussion (4)

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marleythemanzan profile image
Alexander C. Wilcots

To maximize laziness, you can make it into a function called retry() and have the rsync command as the first argument.

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mayeu profile image
Mayeu Author

Yup, but I'm too lazy to maximize my laziness :D

Anyway, if somebody is wondering, something like that should do it (ugly, may be unsafe, you are warned):

function retry() {
  until $1 ;
  do
    echo "Retrying at `date -Iminutes`";
  done
}
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_ajduke profile image
Abhijeet S. Sutar

How about this CLI tool - github.com/nvbn/thefuck

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mayeu profile image
Mayeu Author

Hey, thank you for your reply :)

This is not really the same, thefuck correct spelling errors of the previous command you do. While using until will perpetually re-run the command until the exit code is 0 (i.e.: until it is a success).

In the case of rsync that allow you to continue the download until it succeed :)