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When executing interactively, bash displays the primary prompt PS1 when it is ready to read a  command,  and  the

secondary prompt PS2 when it needs more input to complete a command.  Bash allows these prompt strings to be cus-

tomized by inserting a number of backslash-escaped special characters that are decoded as follows:

\a     an ASCII bell character (07)

\d     the date in “Weekday Month Date” format (e.g., “Tue May 26”)

\D{format}

the format is passed to strftime(3) and the result is inserted into the  prompt  string;  an  empty

format results in a locale-specific time representation.  The braces are required

\e     an ASCII escape character (033)

\h     the hostname up to the first ‘.’

\H     the hostname

\j     the number of jobs currently managed by the shell

\l     the basename of the shell’s terminal device name

\n     newline

\r     carriage return

\s     the name of the shell, the basename of $0 (the portion following the final slash)

\t     the current time in 24-hour HH:MM:SS format

\T     the current time in 12-hour HH:MM:SS format

\@     the current time in 12-hour am/pm format

\A     the current time in 24-hour HH:MM format

\u     the username of the current user

\v     the version of bash (e.g., 2.00)

\V     the release of bash, version + patch level (e.g., 2.00.0)

\w     the current working directory, with $HOME abbreviated with a tilde

\W     the basename of the current working directory, with $HOME abbreviated with a tilde

\!     the history number of this command

\#     the command number of this command

\$     if the effective UID is 0, a #, otherwise a $

\nnn   the character corresponding to the octal number nnn

\\     a backslash

\[     begin  a  sequence  of  non-printing  characters,  which  could be used to embed a terminal control

sequence into the prompt

\]     end a sequence of non-printing characters

-bash-3.2$

-bash-3.2$

-bash-3.2$ PS1='[\u@\h \W]$’

[carl.shen@cvs ~]$

[carl.shen@cvs ~]$

GROUP=`id -gn`

if [ “$USER” = “root” ]; then

PS1='[\[\e[31;1m\]\u\e[0m@\h \W]\$’

else

PS1='[\[\e[34;1m\]\u\e[0m@\h \W]\$’

fi

export PS1