Execute ssh command or bash script sequentally over list of hosts.

mh [hosts specificator] [options] [command...]

Host specificator is:

• :abc: - hosts with tag abc.
• :abc - hosts where tag starts with abc.
• /RE/ - hosts which match regular expression.

All above commands select hosts from config file ~/.mh. Format of ~/.mh file is - first column is host name (and tag), other columns are (just) tags. If you need to specify connection options for hosts, like ssh port, you may specify them in ~/.ssh/config or append to hostname using _ character instead of spaces (ex. mh @alpha_-p222 w).

• @abc,def @ghi user@xyz- manually specify hosts w/o using .mh file.
• @@config - use alternative config file (in format of .mh).

If you don't specify command mh will just print selected hosts (in one row).

Options are:

• --list list selected hosts (one per line) and exit, w/o running command.
• -H suppress hosts prefix in output.
• --vz execute command also in OpenVZ containers on targets using vzctl exec.
• --vz=RE to select only containers where hostname matches RE.
• --script=file execute script file on remotes.
• --edit=file execute script but first run editor over it, if file does not exist it will be created.
• --edit will edit temporary file, execute, and delete it.
• -- end of options separator.
• command... any command as in ssh. When both script and command are used, script will be executed first.

Tips:

• Run ssh command on two hosts: mh @hosta @hostb uname -a or mh @hosta,hostb uname -a or mh @"hosta hostb" uname -a.

• To execute several commands use --edit= option with meaningful script name: mh :web: --edit=install-xyz. No install-xyz is required to exists before run. Second run will edit the same file, so it's useful if you made mistake first time. If you don't need to run editor change command to mh :web: --script=install-xyz.

ssh-agent:

mh tries to use ssh-agent to facilitate passwordless login in this way:

• if ssh-agent is already loaded, it's used and next steps are skipped; otherwise
• if ~/.ssh-agent file exists it's loaded (for ssh-agent socket configuration);
• if it's stale, ssh-agent is started, ~/.ssh-agent is recreated, and ssh-add run.