Terminal Bash

diff¶

differences of 2 stdout outputs¶

diff <(egrep --color "<regexp>" <pathtofile1>) <(egrep --color "<regexp>" <pathtofile2>)

egrep¶

egrep --color "<regexp>" <pathtofile>

Remove lines before and after some strings in a file¶

remove before somestring, retaining somestring¶

awk '/somestring/,0' <pathtofile> > <pathtodeleted_file>

remove after someotherstring, including someotherstring¶

sed -n '/someotherstring/q;p' <pathtofile > <pathtodeleted_file>

Check which ports are busy and which ports are free¶

sudo netstat -tulpn
sudo netstat -antup
sudo lsof -i -n -P
# You can verify process using port /proc:
ls -l /proc/<PID>/exe

List Open Files For Process¶

First you need to find out PID of process. Simply use any one of the following command to obtain process id: ps aux | grep {program-name} OR ps -C {program-name} -o pid=

To list open files for firefox process, enter: ls -l /proc/<PID>/fd

lsof¶

lsof command list open files under all Linux distributions or UNIX like operating system.

Type the following command to list open file for process ID 351: lsof -p 351

Empty the content of a file without closing it¶

truncate -s 0 filename

Calculate total used disk space by files older than 180 days using find¶

From stackoverflow, here an example for space occupied by files older than 5 years (1825 days)

find . -type f -mtime +1825 -printf '%s\n' | awk '{a+=$1;} END {printf "%.1f GB\n", a/2**30;}'