Bash cheatsheet

bash history per user

If you are using ssh public keys for authenticating and want to use a seperate history for each user, you can put this in your .bash_profile:

FINGERPRINT=$(nawk -v ssh_connection="${SSH_CONNECTION}" -v user=${LOGNAME} 'BEGIN{split(ssh_connection,connection)}/.*sshd\[[0-9]+\]: Accepted publickey for/ && $(NF-5)==connection[1] && $(NF-3)==connection[2] {print $NF;}' /var/log/auth.log)

export HISTFILE=.bash_history_${FINGERPRINT:-${SUDO_USER}}

You need to set LogLevel of sshd to VERBOSE in your /etc/ssh/sshd_config:

...
LogLevel VERBOSE
...

bash prompt

Put this in your ~/.bash_profile

typeset +x PS1="\[\e]0;\u@\h: \w\a\]\u@\h:\w# "

Nützliche Variablenersetzungen

dirname

$ myself=/usr/bin/blafasel ; echo ${myself%/*} 
/usr/bin

basename

$ myself=/usr/bin/blafasel ; echo ${myself##*/} 
blafasel

Schleifen

Zahlenfolgen

$ for i in {0..9} ; do echo $i ; done

oder

$ for ((i=0;i<=9;i++)); do echo $i; done

so gehen natürlich auch andere Sprünge, z.B. immer 3 weiter:

$ for ((i=0;i<=9;i+=3)); do echo $i; done

oder oder oder

$ for ((i=0,j=1;i<=9;i+=3,j++)); do echo "$i $j"; done

Rechnen

$ echo $[ 3 + 4 ]  
$ echo $[ 2 ** 8 ] # 2^8