Bash Readline – Configure Up-Arrow to Browse Commands with Same Initial Characters

bashreadline

On the bash command-line, ↑ gives me the previous command. On the command-lines in ipython or matlab, when I type a few characters, ↑ gives me the previously entered command starting with those characters. How can I enable exactly this behaviour in bash?

I am aware of more advanced ways of searching through the command-line history, but sometimes a simple way is more convenient.

Best Answer

The readline commands that you are looking for are the history-search-* commands:

history-search-forward
Search forward through the history for the string of characters between the start of the current line and the current cursor position (the point). This is a non-incremental search.
history-search-backward
Search backward through the history for the string of characters between the start of the current line and the point. This is a non-incremental search.

Binding these in your .inputrc, like so:

"\e[A": history-search-backward            # arrow up
"\e[B": history-search-forward             # arrow down

will allow you to enter the first characters of a command, and then use the Up and Down keys to move through only those commands in your .bash_history that begin with that string.

For example, entering vi and the Up would take you to the first previous command beginning with vi, like vim somefile. Entering Up would take you to the next previous instance, and so on.

You can read more about all of the readline bindings here: http://linux.about.com/library/cmd/blcmdl3_readline.htm

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The command number and the history number are usually different: the history number of a command is its position in the history list, which may include commands restored from the history file (*note Bash History Facilities::), while the command number is the position in the sequence of commands executed during the current shell session.

Diving through the source, in parse.y we see that '\#' resolves to the global static variable current_command_number:

case '#':                                                                     
  n = current_command_number;                                                 
  /* If we have already incremented current_command_number (PS4,              
 ${var@P}), compensate */                                                     
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n--;                                                                          
  temp = itos (n);                                                            
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which only has one other use: in eval.c, it's incremented upon running a command:

# ...
current_command_number++;                                                  

executing = 1;                                                             
stdin_redir = 0;                                                           

execute_command (current_command);

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So I found out what messed it up, and it was not what I expected :)

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Fixed!

(Just btw if somebody else is also having this problem, I have already overridden all the other colors I used with my own definitions using $COLOR=$(tput setaf X) where COLOR is the color you want and X is that color's xterm-256 number.)

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