View source for TcShell

[[Category:Tools]]

The interface between the unix system and the user is called (unix-)'''shell'''. There are in principle many types of shells available. They differ in built-in commands and scripting syntax (e.g. 	
<code>for-loops</code>). However, the commands for basic file operations (<code>cd, cp, rm, ...</code>) are in principle identical and running other programs is done by executing the binary file via <code>./binaryfile</code>. If the binary is located in one of the directories specified in the <code>PATH</code> variable, the program can be executed from every where in the file system without the leading ./

Nearly all unix distributions (Ubuntu, SuSe, ...) are using a different default shell. The default shell on the Remeis computers is the '''TC-shell''', which is based on the C-shell. If you want to know on which shell you are operating right now, type
  echo $SHELL
in, which should result in <code>/bin/tcsh</code>.

= Configuration =

Each user can change the default behavior of the TC-shell via the configuration file ~/.cshrc <br />
This file gets executed each time a new TC-shell is started. Thus changes are applied only after a new shell is opened! The default configuration file looks like

  #!/bin/tcsh -f
  
  set prompt="%n@%m:%~> "
  set nobeep = 1
  set matchbeep = never
  alias l 'ls -l --color=auto'
  alias ls 'ls --color=auto'
  
  # setenv EDITOR jed
  
  if(-d $HOME/bin)  setenv PATH $HOME/bin:$PATH
  
  # LaTeX
  # setenv TEXINPUTS .:~/share/latex::
  # setenv BIBINPUTS .:~/share/bibtex::
  # setenv BSTINPUTS .:~/share/bibtex/bibstyles::
  
  # Astro software
  source /data/system/software/softwarescript.csh
  source $SOFTDIR/softwarescript_Xray.csh

The first line tells the system on which shell the script should be executed. This can be set by
  #!path_to_shell_binary some_options
Of course, the shell here is the TC-shell, located in <code>/bin/tcsh</code>.

= Prompt =

The following block defines some specific variables: <code>prompt</code> defines how your prompt (the information on the left of the command line) should look like. The available place holders are defined as follows:
{| class="wikitable"
| %\  || current directory  
|-
| %~  || current directory with user's home as ~ 
|-
| %n  || username 
|-
| %m  || hostname 
|}
For the default value this results, e.g, in
  username@remeiscomputer:~>
You can also add the output of other commands to the prompt using `command` in the definition. The value "%n@%m:%\> " is equal to
  "`whoami`@`hostname -s`:`pwd`> "

= Default Editor =

The (commented) line
  # setenv EDITOR jed
defines the default editor which is executed if the command <code>$EDITOR</code> is entered. This is important for editors of [[GIT -- The Fast Version Control System|git-repositories]], because <code>git commit</code> calls the in $EDITOR defined command such that the user can enter a comment describing the changes. If this variable is not set or commented, the default editor would be <code>joe</code> or <code>vim</code>. They are very fast editors, but not user-friendly. To uncommment the line just remove the # at the beginning of the line.