25 Quick Linux Command Line Tips - Part 2

[PiNoY]

Following up recent quick linux CLI tip Part 1 here.

 

26. How to print line numbers of each output line of a text file ?

 

# cat -n yourfile.txt

 

27. How to negate a grep result?

 

# grep -v "null" yourfilename

 

28. How to list statistics from your network ?

 

# netstat -s

 

29. What is the country code for a particular country ?

 

# grep -i philippines /usr/share/zoneinfo/iso3166.tab

 

30. How to find out who owns and manages a particular domain ?

 

# whois google.com

 

31. How to get the resolved IP of a domain ?

 

# nslookup google.com

# host google.com

# dig google.com

 

32. How to say hello and goodbye to your system log file ?

 

# logger 'Hello and Goodbye'

 

33. How to list out all your USB current connections ?

 

# lsusb

verbose

# lsusb -v

 

34. How to list out all your PCI card connections ?

 

# lspci

verbose

# lspci -v

 

35. How to lock/unlock a bash enabled user shell account ?

 

# passwd -l useraccount

# passwd -u useraccount

# passwd -S useraccount

 

36. How to limit and change available shell accounts for user's shell assignment ?

 

# vi /etc/shells

 

37. How to change the default values when adding new user accounts ?

 

# vi /etc/default/useradd

 

38. How to create default files automatically every time a new user accounts is created ?

 

# cp /home/pinoy/whateverfile.txt /etc/skel

# useradd -d /home/newuser newuser

 

39. How to go the easy way to home folder of a particular user if you have multinested virtual home folders?

 

# cd ~hisusername

 

40. How to browse and download the whole pages of a particular WWW site in one shot ?

 

# wget -p --progress=dot http://www.google.com

 

41. How to safely mark badblocks from another ext2/ext3 linux harddisk ?

 

# umount /dev/other-harddisk2

# e2fsck -c /dev/other-harddisk2

 

42. How to create a new ext3 filesytem with bad-block checking from your secondary harddisk?

 

# mkfs.ext3 -c /dev/other-harddisk2

 

43. How to compare bzip2 compressed files ?

 

# bzdiff file1 file2

 

44. How to detect hardware monitoring chips and load modules related to newly detected chips?

 

# sensors-detect

>45. How to know if your postfix or sendmail is running ?

 

# ps axuw | grep sendmail

# ps axuw | grep postfix

 

46. How to change the default port when spamassassin is launched?

 

# vi /etc/sysconfig/spamassassin

 

47. How to disable postfix permanently after reboot ?

 

# chkconfig --levels 345 postfix off

 

48. How to know the number of children spawned by apache ?

 

# ps axuw | grep http | wc -l

 

49. How to avoid a module from being loaded by kernel during startup and blacklist it permanently?

 

# vi /etc/modprobe.d/blacklist

 

50. How to quickly count all your queued mail when you box is really hogging due to spam bruteforce attacks and spam mailer?

 

# mailq | wc -l

 

How to smile ?

 

Edited March 30, 2018 by Fearless News