For the time being, the following sections will help you poke
around the shell a bit.
40
Linux First Steps Part I
If you don??™t like your default shell, simply type the name of the shell you want
to try out temporarily. To change your shell permanently, use the usermod
command. For example, to change to the csh shell for the user named chris, type the following as
root user from a shell:
# usermod -s /bin/csh chris
Checking Your Login Session
When you log in to a Linux system, Linux views you as having a particular identity, which includes
your username, group name, user ID, and group ID. Linux also keeps track of your login session: it
knows when you logged in, how long you have been idle, and where you logged in from.
To find out information about your identity, use the id command as follows:
$ id
uid=501(chris) gid=105(sales) groups=105(sales),4(adm),7(lp)
In this example, the username is chris, which is represented by the numeric user ID (uid) 501.
The primary group for chris is called sales, which has a group ID (gid) of 105. The user chris
also belongs to other groups called adm (gid 4) and lp (gid 7). These names and numbers represent
the permissions that chris has to access computer resources. (Permissions are described in
the section ???Understanding File Permissions??? later in this chapter.
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