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25 Quick Linux Command Line Tips - Part 2

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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


# lsusb -v


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


# lspci


# 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 by Fearless News

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