How do i change my prompt string in linux?

  • Linux shells have a way of setting up your prompt string for the shell. When you log into a linux server as non privileged user, by default, you would see this:


    This is the default shell prompt string one, i.e. PS1 environment variable.

    However, there are multiple prompt strings:

    PS1 Is the primary prompt string.
    PS2 Is the secondary prompt string, when a shell needs more information to complete a command.
    PS3 Is used for the select loop inside a script.
    PS4 Is the execution trace prompt, for example when debugging a shell script.

    Note: Generally you only want to customise the default PS1, many users just leave everything as defaults., However, some users go the other customise PS1 with a lot of useful information.

    Some basic examples are:

    Set PS1 to short hostname and username.

    $ PS1="%m: %n> "
    saturn: trainer> 

    Set the PS1 to short hostname, username, and the current working directory.

    $ PS1="%m: %n:%d> "
    saturn: trainer:/home/trainer>
    saturn: trainer:/home/trainer> cd /usr/local
    saturn: trainer:/usr/local>

    Here's some of the options you can use, this is take from the zshmisc man page:, search for "SIMPLE PROMPT ESCAPES"

       Login information
           %l     The line (tty) the user is logged in on, without `/dev/' prefix.
    	      If the name starts with `/dev/tty', that prefix is stripped.
           %M     The full machine hostname.
           %m     The hostname up to the first `.'.  An integer may follow the `%'
    	      to specify how many components  of  the  hostname  are  desired.
    	      With a negative integer, trailing components of the hostname are
           %n     $USERNAME.
           %y     The line (tty) the user is logged in on, without `/dev/' prefix.
    	      This does not treat `/dev/tty' names specially.
       Shell state
           %#     A  `#'  if  the  shell is running with privileges, a `%' if not.
    	      Equivalent to `%(!.#.%%)'.  The definition of `privileged',  for
    	      these  purposes,	is  that either the effective user ID is zero,
    	      or, if POSIX.1e capabilities are supported, that	at  least  one
    	      capability  is  raised  in  either  the Effective or Inheritable
    	      capability vectors.
           %?     The return status of the last command executed just  before  the
           %_     The  status  of the parser, i.e. the shell constructs (like `if'
    	      and `for') that have been started on the command line. If  given
    	      an  integer  number  that  many strings will be printed; zero or
    	      negative or no integer means print as many as there  are.   This
    	      is most useful in prompts PS2 for continuation lines and PS4 for
    	      debugging with the XTRACE option; in the	latter	case  it  will
    	      also work non-interactively.
           %^     The  status  of  the parser in reverse. This is the same as `%_'
    	      other than the order of strings.	It is often used in RPS2.
           %/     Current working directory.  If an integer follows  the  `%',  it
    	      specifies a number of trailing components of the current working
    	      directory to show; zero means the whole path.  A negative  inte‐
    	      ger  specifies leading components, i.e. %-1d specifies the first
           %~     As %d and %/, but if the current working directory  starts  with
    	      $HOME,  that part is replaced by a `~'. Furthermore, if it has a
    	      named directory as its prefix, that part is replaced  by	a  `~'
    	      followed by the name of the directory, but only if the result is
    	      shorter than the full path; see Dynamic and Static named	direc‐
    	      tories in zshexpn(1).
           %e     Evaluation depth of the current sourced file, shell function, or
    	      eval.  This is incremented or decremented every time  the  value
    	      of  %N  is  set  or  reverted to a previous value, respectively.
    	      This is most useful for debugging as part of $PS4.
           %!     Current history event number.
           %i     The line number currently being executed in the script,  sourced
    	      file,  or  shell	function given by %N.  This is most useful for
    	      debugging as part of $PS4.
           %I     The line number currently being executed in the file  %x.   This
    	      is similar to %i, but the line number is always a line number in
    	      the file where the code was defined, even if the code is a shell
           %j     The number of jobs.
           %L     The current value of $SHLVL.
           %N     The name of the script, sourced file, or shell function that zsh
    	      is currently executing, whichever was started most recently.  If
    	      there is none, this is equivalent to the parameter $0.  An inte‐
    	      ger may follow the `%' to specify a number of trailing path com‐
    	      ponents  to  show; zero means the full path.  A negative integer
    	      specifies leading components.
           %x     The name of the file containing the source code currently  being
    	      executed.  This behaves as %N except that function and eval com‐
    	      mand names are not shown,  instead  the  file  where  they  were
           %C     Trailing component of the current working directory.  An integer
    	      may follow the `%' to get more than one component.  Unless  `%C'
    	      is used, tilde contraction is performed first.  These are depre‐
    	      cated as %c and %C are equivalent to %1~ and %1/,  respectively,
    	      while explicit positive integers have the same effect as for the
    	      latter two sequences.

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