Customize your linux bash console: bashrc, aliases, colors, hotkeys, history length

The hidden file .bashrc in each user's home directory (~ or or /home/username or /root) controls the configuration of how the console (and certain commands) behave.

NOTE CENTOS/REDHAT also uses .bash_profile

The shell is the program that interfaces between the user and the Linux kernel. There are different shells with different features.

Ash is a reimplementation of the System V shell May 6, 1989

GNU Bourne Again Shell Bash is an sh-compatible command language interpreter that executes commands read from the standard input or from a file. Bash also incorporates useful features from the Korn and C shells (ksh and csh)

June 18, 1999 Zsh is a command interpreter which mostly resembles the Korn shell. Includes a command-line editor and many other enhancements over the other shells.

Favorite Aliases

Here are my favorite aliases that are in my .bashrc:

alias ssh='ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no'

ssh will not check nor store remote server signatures: insecure!

unalias free or \free

NOTE to escape or override the alias

To enable the new aliases immediately go to the directory type one of the following: . ./bashrc or source ~/.bashrc

nano /home/username/.bashrc or /root/.bashrc export PATH=$PATH:~/bin

.bashrc or .profile are where your shell (BASH) gets it's initial settings:

root:~# ls -al
total 20
drwxr-xr-x  2 root root 4096 Mar 29 21:56 .
drwxr-xr-x 21 root root 4096 Mar 29 22:26 ..
-rw-------  1 root root  183 Mar 29 22:31 .bash_history
-rw-r--r--  1 root root 2225 Mar 29 22:31 .bashrc
-rw-r--r--  1 root root  141 May 15  2007 .profile

if a lot of commands start failing try a cat /etc/passwd and see if you are using /sbin/bash or /bin/sh - the older and less functional shell

NOTE that if you simply use "su" you will only get the normal user path...

increasing bash history length

.bash_profile allows you to customize your command history size... (sometimes it's a section in .bashrc)

if it doesn't exist (e.g. ubuntu can't find it ".bash_profile doesn't exist"), create it and make it executable and then add the following lines...

echo "#defaults are 500" >> .bash_profile
echo "HISTFILESIZE=10000" >> .bash_profile
echo "HISTSIZE=10000" >> .bash_profile    
chmod 700 ~/.bash_profile

HISTFILE is where the history saves to (/dev/null = no history file), the default is: ~/.bash_history.

HISTFILESIZE how many commands to keep in HISTFILE (default 500)

HISTSIZE how many commands to keep in the current session (default 500)

HISTIGNORE Controls which commands to ignorea nd not save. The variable takes a list of colon separated patterns. Pattern & matches the previous history command.

cut -f1 -d" " .bash_history | sort | uniq -c | sort -nr | head -n 30

what command you've typed the most

cut -f1 -d" " /root/.bash_history | sort | uniq -c | sort -nr | head -n 30

what command root has typed the most

cut -f1 /root/.bash_history | sort | uniq -c | sort -nr | head -n 30

what command + parameters root has typed the most

Example default .bash_profile

# Get the aliases and functions
if [ -f ~/.bashrc ]; then
    . ~/.bashrc
fi

# User specific environment and startup programs
PATH=$PATH:$HOME/bin
export PATH

# note this last command only exists in the /root/.bash_profile
unset USERNAME

nano .bashrc

uncomment (remove the leading # from the two lines with --color=auto)

# enable color support of ls and also add handy aliases
if [ "$TERM" != "dumb" ]; then
    eval "`dircolors -b`"
    alias ls='ls --color=auto'
    #alias dir='ls --color=auto --format=vertical'
    #alias vdir='ls --color=auto --format=long'
fi

# ALSO, uncomment the following line to get a color prompt:

# Comment in the above and uncomment this below for a color prompt
#PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[$

And comment out the two lines above it...

hotkeys

Example recycle bin for root

Now you can do fun things like have a "recycle bin" for root:

mkdir /recycle-bin echo "mv $1 /recycle-bin" > del.sh chmod 700 del.sh

AND THEN VERIFY WITH:

1. touch test.txt
2. ./del.sh test.txt
3. ls -al /recycle-bin

bashrc - xterm - ANSI escape color codes

.bashrc

alias xterm1='xterm -fg black -bg white'

nano /home/username/.icewm/toolbar prog xterm xterm1 x-terminal-emulator

nano /home/username/.icewm/keys

key "Ctrl+Alt+j" xterm -fg black -bg white

FIRST print out what colors are available...

dircolors -p > dircolors.txt

after reading through that and being thoroughly mystified...

echo -e "\033[44;37;5m ME \033[0m COOL"

if you put the above into your bash shell you'll see that the ANSI control of colors is basically what controls BASH/TERMINALS...

Attribute codes:
00=none 01=bold 04=underscore 05=blink 07=reverse 08=concealed

Text color codes:
30=black 31=red 32=green 33=yellow 34=blue 35=magenta 36=cyan 37=white

Background color codes:
40=black 41=red 42=green 43=yellow 44=blue 45=magenta 46=cyan 47=white

Black       0;30     Dark Gray     1;30
Blue        0;34     Light Blue    1;34
Green       0;32     Light Green   1;32
Cyan        0;36     Light Cyan    1;36
Red         0;31     Light Red     1;31
Purple      0;35     Light Purple  1;35
Brown       0;33     Yellow        1;33
Light Gray  0;37     White         1;37

echo -e "\e[1;34mThis is a blue text.\e[0m"

so \e[attribute code; text color code0m

framed by the [ --- 0m 
note that the \033 in the first example has been replaced by \e

echo -e "\e[30;470mtest"

FOREGROUND WHITE (in case you accidentally set it to black on black)
echo -e "\033[37m\]"

BACKGROUND WHITE
echo -e "\033[47m\]"

FOREGROUND BLACK
echo -e "\033[1;30m\]"



changing the foreground and background color of your bash shell
(and font?)

TEMPORARY SOLUTION

xterm -fg *color* -bg *color*

PERMENANT SOLUTION


.Xdefaults file in your home directory