5 ms·

meh... for h in host1 host2 host3; do \ echo -e "\n$h\n===========\n"; \ ssh $h 'ln -s /some/path /path/to/link && ls -l /path/to/link'; \

by ilikepi 16y ago

meh... for h in host1 host2 host3; do \ echo -e "\n$h\n===========\n"; \ ssh $h 'ln -s /some/path /path/to/link && ls -l /path/to/link'; \ done edit: woops, left out a couple semicolons...

geocar 16y ago
> edit: woops Exactly. One-offs are easy to test interactively with cssh, and despite what anyone thinks, there are always one-offs in the real world.
- ilikepi 16y ago
  True. Usually when creating a shell loop like this, I prepend 'echo' in front of 'ssh...' as a dry run first. I also wouldn't actually use something like this for commands that are destructive in nature. Usually it's for things like running informational commands ('rpm -q', 'uptime', etc). Of course anything can become destructive if you fat-finger it hard enough. In short, use automation with care.
fragsworth 16y ago
FUCKING SERIOUSLY?! Thank you for this comment, I never knew you could pass commands to ssh.
- joh6nn 16y ago
  i suggest perusing the ssh man, then, as it seems likely that it has other capabilities you don't know about.
  - rbranson 16y ago
    Like how SSH agent forwarding can allow you to hop from box to box with the SSH keys loaded onto your local machine's SSH agent? Found that one a few months ago, made me reflect on what I've been doing in life the past 10 years not thoroughly reading UNIX man pages.
    - erikig 16y ago
      Thanks for this one. You just added a few days to my life and helped push out the onset of carpal tunnel/arthritis. ~ http://www.unixwiz.net/techtips/ssh-agent-forwarding.html http://www.unixwiz.net/techtips/ssh-agent-forwarding.html
  - jberryman 16y ago
    ssh is magic. checkout -X for X11 forwarding to run remote GUI apps, and -R which lets you set up a reverse SSH tunnel when you need to connect to a machine behind a firewall.
  - Raphael_Amiard 16y ago
    such a polite version of RTFM, i love you
- taylorbuley 16y ago
  Based on a similar reaction a few months ago, this will definitely change the way you go about system work.
- z2amiller 16y ago
  Now combine that with dsh (http://www.netfort.gr.jp/~dancer/software/dsh.html.en http://www.netfort.gr.jp/~dancer/software/dsh.html.en) and authorized_keys, you can _really_ get in trouble. dsh is similar to this Cluster SSH, but is appropriate for use in scripts, cron jobs, etc. Example: dsh -Mg all-machines -F 20 'do something' -M: Prepend any line of output with the machine that emitted it -g: runs the group all-machines (just a text file in etc/dsh/group) -F 20: forks at most 20 copies of ssh in the background so you don't overload the server you're running this from
veritgo 16y ago
You probably already know this, but if you have a significant number of hosts: for i in `seq 1 30`; do \ echo -e "\nhost$i\n===========\n"; \ ssh host$i 'ln -s /some/path /path/to/link && ls -l /path/to/link'; \ done Also, if you just start typing for i in `seq 1 30` do commands more commands done On the command line itself, you don't need to worry about semicolons. Bash will take care of it.
- jseban 16y ago
  for i in {1..30}; do...
- ilikepi 16y ago
  Ah, I was not aware of seq; good one. :) Good point about not needing semicolons for multiple-line stuff (assuming the EOL's are not escaped, as you have it in your example). I blame the PHP I spent all week immersed in...bleh.

by ilikepi 16y ago

meh... for h in host1 host2 host3; do \ echo -e "\n$h\n===========\n"; \ ssh $h 'ln -s /some/path /path/to/link && ls -l /path/to/link'; \ done edit: woops, left out a couple semicolons...

geocar 16y ago

> edit: woops Exactly. One-offs are easy to test interactively with cssh, and despite what anyone thinks, there are always one-offs in the real world.

ilikepi 16y ago
True. Usually when creating a shell loop like this, I prepend 'echo' in front of 'ssh...' as a dry run first. I also wouldn't actually use something like this for commands that are destructive in nature. Usually it's for things like running informational commands ('rpm -q', 'uptime', etc). Of course anything can become destructive if you fat-finger it hard enough. In short, use automation with care.

fragsworth 16y ago

FUCKING SERIOUSLY?! Thank you for this comment, I never knew you could pass commands to ssh.

joh6nn 16y ago
i suggest perusing the ssh man, then, as it seems likely that it has other capabilities you don't know about.
- rbranson 16y ago
  Like how SSH agent forwarding can allow you to hop from box to box with the SSH keys loaded onto your local machine's SSH agent? Found that one a few months ago, made me reflect on what I've been doing in life the past 10 years not thoroughly reading UNIX man pages.
  - erikig 16y ago
    Thanks for this one. You just added a few days to my life and helped push out the onset of carpal tunnel/arthritis. ~ http://www.unixwiz.net/techtips/ssh-agent-forwarding.html http://www.unixwiz.net/techtips/ssh-agent-forwarding.html
- jberryman 16y ago
  ssh is magic. checkout -X for X11 forwarding to run remote GUI apps, and -R which lets you set up a reverse SSH tunnel when you need to connect to a machine behind a firewall.
- Raphael_Amiard 16y ago
  such a polite version of RTFM, i love you
taylorbuley 16y ago
Based on a similar reaction a few months ago, this will definitely change the way you go about system work.
z2amiller 16y ago
Now combine that with dsh (http://www.netfort.gr.jp/~dancer/software/dsh.html.en http://www.netfort.gr.jp/~dancer/software/dsh.html.en) and authorized_keys, you can _really_ get in trouble. dsh is similar to this Cluster SSH, but is appropriate for use in scripts, cron jobs, etc. Example: dsh -Mg all-machines -F 20 'do something' -M: Prepend any line of output with the machine that emitted it -g: runs the group all-machines (just a text file in etc/dsh/group) -F 20: forks at most 20 copies of ssh in the background so you don't overload the server you're running this from

veritgo 16y ago

You probably already know this, but if you have a significant number of hosts: for i in `seq 1 30`; do \ echo -e "\nhost$i\n===========\n"; \ ssh host$i 'ln -s /some/path /path/to/link && ls -l /path/to/link'; \ done Also, if you just start typing for i in `seq 1 30` do commands more commands done On the command line itself, you don't need to worry about semicolons. Bash will take care of it.

jseban 16y ago
for i in {1..30}; do...
ilikepi 16y ago
Ah, I was not aware of seq; good one. :) Good point about not needing semicolons for multiple-line stuff (assuming the EOL's are not escaped, as you have it in your example). I blame the PHP I spent all week immersed in...bleh.