1. How to have a stop watch scenario from command line terminal?
# time cat
2. How to measure the time of executing any executable command?
# time firefox
wait 5 seconds and close the application
3. How to CD to a user's home directory?
# cd ~userhome
4. How to CD back to home folder of a currently logged in user?
5. How to CD back to previous directory?
# cd -
6. How to show all active host IP address?
# ip address
7. How to list out all your iptables rules?
# iptables -L
8. How to save your currently loaded firewall iptable rules?
9. How to download a file using wget?
# wget -c "http://website.com/file.rpm"
10. How to limit your download rate with wget?
# wget --limit-rate=30k "http://vertito.com/file.rpm"
11. How to download multiple files in one shot?
# wget -c "ftp://vertito.org/file[1-9].iso
12. How to find windows machine with shared folders?
13. How to look for windows netbios name?
# nmblookup -A windows-ip-address
14. How to browse for computers like network neighborhood does?
15. How list folder shared by a particular windows machine?
# smbclient -L windows-machine
16. How to diplay calendar without X?
# cal -3
17. How to list out all harddisk partition?
# cat /proc/partitions
# fdisk -l
18. How to list out all mounted and labeled harddisk partition?
# mount -l
19. How to show host reboot history?
# last reboot
20. How to get CPU info?
# cat /proc/cpuinfo
21. How to show all interrupts?
# cat /proc/interrupts
22. How to show last successful login users?
23. How to search for a yet unknown package from web repo?
# yum search *packagemaybe*
# yum whatprovides packagemaybe
24. How to setup a shell with yum?
# yum shell
25. How to use yum locally?
# yum localinstall packagename
26. How to find file with 750 file permission?
# find / -type f -perm 750
27. How to find all files not owned by any user?
# find / -nouser
28. How to find all files owned by a user?
# find /home -user vertito
29. How to find files by group name?
# find /home -group vertito
30. How to change timestamp of a file?
# touch -c -t 0707280337 testfile.txt
31. How to change ownership of a file?
# chown user1:user1 testfile.txt
32. How to set user password details and expiration?
# chage username
33. How to change default home directory of a user?
# usermod -d /new-default-directory username
34. How to change a user finger information?
# chfn username
35. How to change a user shell information?
# chsh username
36. How to change file mode bits?
# chmod testfile.txt
37. How to change and update (multiple) user passwords in batch mode?
38. How to make an ISO image from contents of a directory?
# mkisofs -V label-name -r directory-name > iso-image.iso
39. How to make an ISO image from contents of a directory and zip it in one shot?
# mkisofs -V label-name -r directory-name | gzip > iso-image.iso.gz
40. Oh, how to eject a DVD/CD disk from a mounted DVD/CD drive?
41. How to clear or erase all data from a mounted DVDRW / CDRW disk?
# cdrecord -v dev=/dev/cdrom blank=fast
42. How to add an ext3 journal to a filesystem ?
# tune2fs -j /dev/sdb1
43. How to create ext2/ext3 filesystem with bad block checking?
# mkfs.ext3 -c /dev/sdb1
# mkfs.ext2 -c /dev/sdb1
44. How to combine and sort multiple raw files in one shot?
# sort file1 file2 | uniq > newfile
45. How to compare two text files?
# diff file1 file2
46. How to get more memory information?
# cat /proc/meminfo
47. How to get the maximum number of threads of your host?
# cat /proc/sys/kernel/threads-max
48. How to get the file properties of a file or folder?
# stat testfile.txt
# stat foldername
49. How to backup harddisk to another host via ssh?
# dd bs=1M if=/dev/sda | gzip | ssh username@remote-ip-address 'dd of=hda.gz'
50. How to run a command as another user?
# runuser another-user script-name-or-program
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