[SOLVED] Is there a cli method of running a command twice without having to type it twice?

powderburns · 03-23-2017, 01:14 PM

I'm doing some backups with rsync over wifi and I am dealing with broken pipes by running my command multiple times, but typing out the command twice separated by a ; or && is tedious without being able to copy & paste the command. Is there a trick to tell my shell to run the command n times instead of writing out

Code:

rsync arguments source destination ; rsync arguments source destination

?

eta: I also just realized this would prompt me for a password each time rsync is run, any way around that?

kakistocrat · 03-23-2017, 01:21 PM

Depends on the shell. In many you can just press the up arrow. Also in many you can press !! and it will repeat the last one again.

Code:

date;
!!

date; !!

If you are searching through your command history, ctrl-R will search backwards for you.

kakistocrat · 03-23-2017, 01:34 PM

Or you can run rsync in a loop until it succeeds.

Code:

while ! rsync -options source/ destination/; do true; done;

That way it will keep trying until the transfer is completed successfully.

powderburns · 03-24-2017, 09:02 AM

Both suggestions worked great. I finished my remaining transfers without having to supervise the shell all night. Thanks for your help!

kakistocrat · 03-24-2017, 09:55 AM

No worries. It's a trick that also works with ssh if you use that as well. It needs tmux or screen over on the server and key-based authentication is prerequisite.

Code:

ssh-add ~/.ssh/server_key_ed25519

while ! ssh -t -i ~/.ssh/server_key_ed25519 server.example.com 'tmux a || tmux'; do sleep 1; done;

Useful when traveling or in other situations where connectivity is irregular.