Can I do ssh and do for loop and touch files in a single shot?

Question

for account in ${accounts}
do
        `ssh -q id@server "touch EVENTS_${account}_${date}.log"`
done

Instead of doing ssh so many times, can I just do ssh and run the for loop and touch the files?

Answer 1

ssh allows you to execute multiple commands. Simply separate each command with a semi-colon.

command=": "
for account in ${accounts}
do
        command=$command"; touch EVENTS_${account}_${date}.log"
done
ssh -q id@server "$command"

All the ": " does is says "proceed to the next command." It's so you're not starting your command with a semi-colon.

Also, you don't need backticks around that command.

Answer 2

Run the loop on the remote machine.

ssh -q id@server "for account in ${accounts}; do touch EVENTS_\${account}_${date}.log; done"

Note that I assume that $accounts and $date don't contain any shell special characters ("$'()&;<>[\]`{|}~). In paricular, $accounts will be interpolated into the remote shell then interpreted there. If you need to protect special characters, you need to be more careful with the quoting:

q=\'\\\'\'  # '\'' effectively quotes a single quote inside single quotes
ssh -q id@server 'for account in '\'"${accounts//\'/$q}"\''; do touch "EVENTS_${account}_${date}.log"; done'

Alternatively, mount the remote filesystem with sshfs and work on it as you would locally.

mkdir mnt
sshfs id@server mnt
for account in ${accounts}; do touch "mnt/EVENTS_\${account}_${date}.log"; done

Answer 3

Cluster ssh seems like the perfect tool for what you are trying to do.

ClusterSSH is a tool for making the same change on multiple servers at the same time. The 'cssh' command opens an administration console and an xterm to all specified hosts. Any text typed into the administration console is replicated to all windows. All windows may also be typed into directly.

This tool is intended for (but not limited to) cluster administration where the same configuration or commands must be run on each node within the cluster. Performing these commands all at once via this tool ensures all nodes are kept in sync.