CHAPTER 5 Shells
A simple .profile could be the following:
PATH=/usr/bin:/usr/ucb:/usr/local/bin:. # set the PATH
export PATH # so that PATH is available to subshells
# Set a prompt
PS1="{`hostname` `whoami`} " # set the prompt, default is "$"
# functions
ls() { /bin/ls -sbF "$@";}
ll() { ls -al "$@";}
# Set the terminal type
stty erase ^H # set Control-H to be the erase key
eval `tset -Q -s -m ':?xterm'` # prompt for the terminal type, assume xterm
#
umask 077
Whenever a # symbol is encountered the remainder of that line is treated as a comment. In the PATH variable each directory is separated by a colon (:) and the dot (.) specifies that the current directory is in your path. If the latter is not set it's a simple matter to execute a program in the current directory by typing:
./program_name
It's actually a good idea not to have dot (.) in your path, as you may inadvertently execute a program you didn't intend to when you cd to different directories.
A variable set in .profile is set only in the login shell unless you "export" it or source .profile from another shell. In the above example PATH is exported to any subshells. You can source a file with the built-in "." command of sh, i.e.:
. ./.profile
You can make your own functions. In the above example the function ll results in an "ls -al" being done on the specified files or directories.
With stty the erase character is set to Control-H (^H), which is usually the Backspace key.
The tset command prompts for the terminal type, and assumes "xterm" if we just hit <CR>. This command is run with the shell built-in, eval, which takes the result from the tset command and uses it as an argument for the shell. In this case the "-s" option to tset sets the TERM and TERMCAP variables and exports them.
The last line in the example runs the umask command with the option such that any files or directories you create will not have read/write/execute permission for group and other.
For further information about sh type "man sh" at the shell prompt.