Os - Shell in Linux context
The valid shell for a distribution are listed in the /etc/shells
/bin/sh /bin/bash /sbin/nologin /bin/tcsh /bin/csh /bin/ksh
Several type of wiki/unix_shell have been developed:
The following table shows the commonly used default UNIX® system prompt and superuser prompt for the C shell, Bourne shell, and Korn shell.
|C shell for superuser||machine_name#|
|Bourne shell and Korn shell||$|
|Bourne shell and Korn shell for superuser||#|
With the environment variable SHELL
ps -p $$
PID TTY TIME CMD 4104 pts/1 00:00:00 bash
- $ is a bash special parameter that contains the PID (process identification number) of the current process which is your shell
Then running a ps on that number displays a process status listing of your shell.
In bash, the special parameter 0 expands to the name of the shell or shell script. This is set at shell initialization. If bash is invoked with a file of com- mands, 0 is set to the name of that file.
If bash is started with the -c option, then 0 is set to the first argument after the string to be executed, if one is present. Otherwise, it is set to the file name used to invoke bash, as given by argument zero.
# echo $0
default shell for a user
The utility chsh (Change the login shell) is used to change it.
It will change it in the /etc/password file
absolute path name
See the special parameter _