One thing that comes up a lot during system administration is the monitoring of several machines. It's not uncommon to have 5 or 6 ssh
sessions open at a time, more if you have multiple monitors. It's crucial to know which session is running on which machine, as typing the right command on the wrong machine can be a disaster. For this reason and others, I recommend using a custom PS1
variable when logging into a remote machine.
This was mentioned in Chapter 1, Using the Terminal / Command Line, during the discussion of environment variables. The following is what my PS1
variable looks like on my machine running Fedora 17:
Big2 /temp/linuxbook/chapA # echo $PS1 Big2 \w # Big2 /temp/linuxbook/chapA #
Simple, and not too cluttered. The following is what PS1
looks like on my other machine when I log into it:
BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 /temp # echo $PS1 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 \w # BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 /temp #
It should be pretty hard to mix those up.
While we are on the subject of environment variables, there is something else to keep in mind. When you make a change to your .bashrc
file and source it, the changes are only visible in that session (as well as any newly opened sessions). In order to see the change in other existing sessions you must source it in them as well. It would be rather cool if there was a way to make the changes visible in every session with just one command, however, I do not believe that is possible. Of course, one could argue that shutdown -r
now will do it.