Tips and tricks

August 11, 2006


Q:- Find out top 10 directories eating up your disk space:
A:- du -csh * –max-depth=0 | sort -rn | head -10

Q:- Find Harddisk Capacity on the box.
A:- fdisk -l | grep -iE ‘mb|gb|tb’

Q:- Find out performance of your hard disk with following command:
A:- hdparm -t -T /dev/hda

Q:- You can block all login access with following command:
A:- touch /etc/nologin

Q:- It is good idea to encrypt backup made with tar command:
A:- tar -zcvf – *| openssl des3 -salt -k PASSWORD | dd of=mybackup.tbz
tar zcvf – /home |openssl des3 -salt -k PASSWORD | dd of=/dev/st0
To extract encrypted tar file use command:
dd if= mybackup.tbz |openssl des3 -d -k PASSWORD| tar zvxf –
dd if=/dev/st0|openssl des3 -d -k PASSWORD | tar xzf ————————————————————————

Q:- Delete a file securely, first overwriting it to hide its contents.
A:- $ shred -n 200 -z -u personalinfo.tar.gz
A:- srm filename
A:- wipe filename
Q:- Delete file by inode:
A:- $ find . -inum 782263 -exec rm -i {} \;

Q:- Forcefully unmount CD/DVD Rom or any other mounted partitions with
fuser command:
Ans:- fuser -km /dev/cdrom
fuser -km /mnt/cdrom\n
fuser -km /data2

Q: List open files under user nobody

A:- lsof -u nobody


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