On 4/8/09, Mark Carlson <[email protected]> wrote: > On 4/8/09, Greg Saunders <[email protected]> wrote: > > Hi all, I'm looking for the best way to run a remote process. SSH with > keys? > > "ssh [email protected] remoteprocess" > > > > Is there a better way, especially if you have to execute 20 remote commands > > each time and those commands are determined on the fly and not known ahead > > of time. > > > > Thanks! > > Greg > > > "best" really depends on your situation... > > Personally, I find SSH to be the best for me. If you need to use > keys, use them, if you don't want to, don't. > > If you want to execute 20 commands, use a list of commands. > > Some simple examples: > # Commands are executed sequentially: > % command1; cmd2; cmd3 > # Commands are only executed if the previous one returns zero: > % command1 && cmd2 && cmd3 > # Commands are only executed if the previous one returned nonzero (error): > % command1 || cmd2 || cmd3 > > A more complex example: > # Run command 1, then command 2, and finally command 3 only if command > 2 did not return an error > % command1; cmd2 && cmd3 > > > From the bash man page: http://linux.die.net/man/1/bash > ---------------------------------------- > Shell Grammar > <...> > > Lists > > A list is a sequence of one or more pipelines separated by one of the > operators ;, &, &&, or ||, and optionally terminated by one of ;, &, > or <newline>. > > Of these list operators, && and || have equal precedence, followed by > ; and &, which have equal precedence. > > A sequence of one or more newlines may appear in a list instead of a > semicolon to delimit commands. > > If a command is terminated by the control operator &, the shell > executes the command in the background in a subshell. The shell does > not wait for the command to finish, and the return status is 0. > Commands separated by a ; are executed sequentially; the shell waits > for each command to terminate in turn. The return status is the exit > status of the last command executed. > > The control operators && and || denote AND lists and OR lists, > respectively. An AND list has the form > command1 && command2 > command2 is executed if, and only if, command1 returns an exit status of > zero. > > An OR list has the form > command1 || command2 > command2 is executed if and only if command1 returns a non-zero exit > status. The return status of AND and OR lists is the exit status of > the last command executed in the list. > > -Mark C. >
Oh, and if you don't use quotes to enclose the commands, you may be surprised by the results! Ex: both commands run on remote machine: % ssh 127.0.0.1 "echo hello; echo world" Ex: "echo hello" run remotely, "echo world" run locally % ssh 127.0.0.1 echo hello; echo world The results look the same in this case... but if your commands are backing up a computer or something, you will soon notice a difference! -Mark C. _______________________________________________ clug-talk mailing list [email protected] http://clug.ca/mailman/listinfo/clug-talk_clug.ca Mailing List Guidelines (http://clug.ca/ml_guidelines.php) **Please remove these lines when replying
