bash history - ignore duplicate & commands

put these lines in your .bash_profile to ignore duplicate history or to ignore certain commands.
and it also keep your history short :)

# ignore duplicate
HISTCONTROL=ignoreboth

# ignore these commands in history file
HISTIGNORE=ls:ll:la:l:cd:pwd:exit:mc:su:df:clear

bash tip: search command history

from my previous post on ksh hotkeys vs bash hotkeys, i mentioned on how to use hot key to do search on command history, which is using ctrl-r
but i also mentioned that i'm not sure on how to use this key to go to the next or previous match command. i found it now :)

once you hit ctrl-r to do a "reverse incremental search". as you type, bash will search your command history and auto-fill the most recent command that matches the pattern you type in. hit ctrl-r again to go to the next most recent match. just hit ctrl-r again & again until you found the command you looking for. and if you want to go the previous match command, you can hit ctrl-s, but make sure you do this first:

disable the default terminal setting for ctrl-s & ctrl-q which is to lock & unlock your terminal.

$ stty -ixon

unix tip: ksh hotkeys vs bash hotkeys

a few of our servers are running ksh shell instead of bash. sometimes i have
problems handling ksh hotkeys because getting used to bash hotkeys like below:

bash hotkeys:
ctrl-l  -- clear screen
ctrl-r  -- does a search in the previously given commands so that
         you dont have to repeat long command.
ctrl-u  -- clears the typing before the hotkey.
ctrl-a  -- takes you to the begining of the command you are
         currently typing.
ctrl-e  -- takes you to the end of the command you are currently
         typing in.
esc-b   -- takes you back by one word while typing a command.
ctrl-c  -- kills the current command or process.
ctrl-d  -- kills the shell.
ctrl-h  -- deletes one letter at a time from the command you are
         typing in.
ctrl-z  -- puts the currently running process in background, the
         process can be brought back to run state by using fg
         command.
esc-p   -- like ctrl-r lets you search through the previously
         given commands.
esc-.   -- gives the last command you typed.
tab     -- auto completion
Read more...

below are the hotkeys when i'm using ksh shell (you have to 
set -o vi first)

ksh hotkeys:
esc-\   -- auto completion. only work if the file/command is in
         current directory
esc-k   -- scroll up
esc-j   -- scroll down
esc-/   -- search in the previously given commands (esc-/ keyin
         the command you want search & enter. press n or N to
         go to the next or previous command, even ctrl-r in bash
         can't go to the next or previous command or maybe i just
         don't know how.
esc-=   -- filename check - this is cool!!!

since its using vi mode, you can also edit the commands 
using below keys
esc-l   -- forward one character
esc-h   -- backward one character
esc-x   -- delete one character
esc-r   -- replace one character
esc-e   -- forward end of word
esc-b   -- backward beginning of word
esc-d   -- delete to end of line
esc-i   -- insert text (current space)
esc-a   -- insert text (adjacent space)
esc-^   -- move cursor to beginning of line
esc-$   -- move cursor to end of line
note:
esc key is not necessary if you are currently in command-mode