Useful commands

This post summarizes few interesting and useful commands, some of them are from commandlinefu page.


Capture video of a linux desktop:

• ffmpeg -f x11grab -s wxga -r 25 -i :0.0 -sameq /tmp/out.mpg

Watch Network Service Activity in Real-time

• lsof -i

Close shell keeping all subprocess running

• disown -a && exit

Sharing file through http 80 port

• nc -v -l 80 < file.ext

Put a console clock in top right corner

• while sleep 1;do tput sc;tput cup 0 $(($(tput cols)-29));date;tput rc;done &

Send a message to everybody’s terminal

• wall [message]

Add Password Protection to a file your editing in vim

• vim -x <FILENAME>

How to copy CD/DVD to hard disk (.iso)

• dd if=/dev/cdrom of=whatever.iso

• readom dev=/dev/scd0 f=/path/to/image.iso

Create a pdf version of a manpage

• man -t manpage | ps2pdf - filename.pdf

Remove security limitations from PDF documents using ghostscript

• gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=OUTPUT.pdf -c .setpdfwrite -f

Run a file system check on your next boot

• sudo touch /forcefsck

Print a specific line from a file

• sed -n 5p <file>

Convert PDF to JPG

• for file in `ls *.pdf`; do convert -verbose -colorspace RGB -resize 800 -interlace none -density 300 -quality 80 $file `echo $file | sed 's/\.pdf$/\.jpg/'`; done

Press Any Key to Continue

• read -sn 1 -p "Press any key to continue..."

A child process which survives the parent's death (for sure)

• ( command & )

Pretend to be busy in office to enjoy a cup of coffee

• cat /dev/urandom | hexdump -C | grep "ca fe" (this is CPU consumming)

• while [ true ]; do sleep 1; head -n 100 /dev/urandom | hexdump -C | grep "ca fe"; done

Guess the number...

• A=1;B=100;X=0;C=0;N=$[$RANDOM%$B+1];until [ $X -eq $N ];do read -p "N between $A and $B. Guess? " X;C=$(($C+1));A=$(($X<$N?$X:$A));B=$(($X>$N?$X:$B));done;echo "Took you $C tries...";

Simple http server on 8080 (all interfaces)

• python -m SimpleHTTPServer 8080

Currently mounted filesystems in nice layout

• mount | column -t

Make 'less' behave like 'tail -f'

• less +F somelogfile

• Using +F will put less in follow mode. This works similar to 'tail -f'. To stop scrolling, use the interrupt. Then you'll get the normal benefits of less (scroll, etc.). Pressing SHIFT-F will resume the 'tailling'.

Display number of connections to MySQL DB

• mysql -u root -p -BNe "select host,count(host) from processlist group by host;" information_schema