Bash

Some one liners and stuff for bash.

Config Files without comments or blank lines

alias catconf="grep -v '^$\|^\s*\#'"

DateStamp

date +%Y_%m_%d

tar czvf Ansible_`date +%Y_%m_%d`.tgz /home/ansible/ --exclude 'ansible.log'

tar czvf `hostname`_`date +%Y_%m_%d`.tgz /home/ansible/ --exclude 'ansible.log'

Uptime as a datestamp

date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%Y/%m/%d %H:%M"

#Determine if it is an odd or even week

weeknumber=$(echo "(`date +%d` / 7 + 1)" | bc )

if [ $weeknumber == 1 ]; then

echo "don't run on first week of month. exiting"

exit

echo $week

if [ $(echo $(( $weeknumber % 2 ))) == 0 ]; then

week=even

else

week=odd

Backspace

stty -a

Set backspce

stty erase ^?

History

C-r #Ctrl R

Reverse search through history

Brace Expansion

touch {jan,feb,mar}-{report,expense}.txt

Create 2 files for each of the 3 months.

Linux Performance tools

http://www.youtube.com/watch?v=t0XDEAECObA&feature=player_embedded

apt-get install sysstat

CPU

vmstat

mpstat -P ALL

top

sar

iostat

Disk

apt-get install bonnie++

prompt

vi ~/.bash_profile

PS1="\[\033[01;37m\]\$? \$(if [[ \$? == 0 ]]; then echo \"\[\033[01;32m\];)\"; else echo \"\[\033[01;31m\];(\"; fi) $(if [[ ${EUID} == 0 ]]; then echo '\[\033[01;31m\]\h'; else echo '\[\033[01;36m\]\u@\h'; fi)\[\033[01;35m\] \w \$\[\033[00m\] "

Tar

Create a gziped tar file

tar czvf blah.tgz /home/kevin/

tar czvf Ansible_`date +%Y_%m_%d`.tgz /home/kevin/ --exclude 'ansible.log' --exclude 'sendmailanalyzer-9.0.tar.gz' --exclude '/home/kevin/sendmailanalyzer-9.0'

List the contents of a tarball

tar -tvf blah.tgz

Untar

tar -xvf blah.tgz

Sed

find and replace in multiple files

find . -name "run_*" -exec sed -i "s/chmod a/chmod -R a/g" '{}' \;

Find a matching line in a file and append the contents of another file to that line

for f in *

echo "Processing $f file..."

#http://www.grymoire.com/Unix/Sed.html

#get the contents of the file and remove spaces to make the following sed work properly

filecontents=$(cat $f | sed 's/ //g')

#sed -i for inplace

#broken into multiple quoted or double quoted sections to handle variables properly

#the first backslash is to denote the next character will be the delimiter or underscore in this case

#find a line that starts with $f

#then add the contents of the file to the end of that line

sed -i '\_^'$f"_ s_\$_"$filecontents'_' $tmpserverlist

filecontents=""

cat $f

done

Sort

Sort on the first column 15th character

sort -k 1.15

Capturing Time to run a command into a variable

https://bbs.archlinux.org/viewtopic.php?id=155044

t=$({ time sleep 1 >/dev/null 2>&1;} 2>&1 )

echo $t

split substring

http://stackoverflow.com/questions/918886/how-do-i-split-a-string-on-a-delimiter-in-bash

Split string based on delimiter in shell

But if you would write something useable under many shells, you have to not use bashisms.

There is a syntax, used in many shells, for splitting a string accros first or last occurence of a substring:

${var#*SubStr} # will drop begin of string upto first occur of `SubStr`

${var##*SubStr} # will drop begin of string upto last occur of `SubStr`

${var%SubStr*} # will drop part of string from last occur of `SubStr` to the end

${var%%SubStr*} # will drop part of string from first occur of `SubStr` to the end

reverse diff

find matching lines

fgrep -xf file1 file2

netcat nc

http://www.rackspace.com/knowledge_center/article/testing-network-services-with-netcat

nc -vz machine port