Recently I was working on a Nokia’s LTE & UMTS Automated Operations and Recovery (AOR), a product which simplifies service operations by automating network supervisory activities . I had a team from diverse background like transmission,RF,Core,Networks,Java developers,Database and our task was to test Linux based opensource application which obviously needed good knowledge of Linux CLI.
Linux Command-Line provides a richer experience in terms of speed and expressiveness. Linux Operating system is most popular operating systems to run server-side applications,telecom NFV, Openstack, Dockers,Kubernetes,Database and Web based applications.In fact almost all Java applications are running on Linux.The telecom equipment’s uses Linux as Network operating system, as an example Juniper routers running JUNOS which runs Linux natively. Linux is very popular on embedded platforms too. So lets get on to the Linux commands compilation .
- Working with the file
Search And Replace in the file :s/raga/namo/g
Find each occurrence of ‘raga’ (in the current line only), and replace it with ‘namo’.
Find each occurrence of ‘raga’ (in all lines), and replace it with ‘namo’.
Change each ‘raga’ to ‘namo’, but get the confirmation first.
Change only whole words exactly matching ‘raga’ to ‘namo’; ask for confirmation.
Change each ‘raga’ (case insensitive due to the i flag) to ‘namo’; ask for confirmation.
:%s/raga\c/namo/gc is the same because \c makes the search case insensitive.
This may be wanted after using :set noignorecase to make searches case sensitive (the default). To remove all the lines above the current cursor position use command dgg where d is the deletion command, and gg is a movement command that says go to the top of the file, so when used together, it means delete from my current position to the top of the file. Similarly dG will delete all lines at or below the current one . In summary dgg and dG are the commands to use.
vi filename edit a file named "filename" vi newfile create a new file named "newfile"
i insert text left of cursor a append text right of cursor
MOVING THE CURSOR
h left one space j down one line k up one line l right one space
x delete character nx delete n characters X delete character before cursor dw delete word ndw delete n words dd delete line ndd delete n lines D delete characters from cursor to end of line r replace character under cursor cw replace a word ncw replace n words C change text from cursor to end of line o insert blank line below cursor (ready for insertion) O insert blank line above cursor (ready for insertion) J join succeeding line to current cursor line nJ join n succeeding lines to current cursor line u undo last change U restore current line
MOVING AROUND IN A FILE
w forward word by word b backward word by word $ to end of line 0 (zero) to beginning of line H to top line of screen M to middle line of screen L to last line of screen G to last line of file 1G to first line of file <Control>f scroll forward one screen <Control>b scroll backward one screen <Control>d scroll down one-half screen <Control>u scroll up one-half screen n repeat last search in same direction N repeat last search in opposite direction
CLOSING AND SAVING A FILE
ZZ save file and then quit :w save file :q! discard changes and quit file
To empty the file use “> file.txt” in command mode, where file.txt is your file name
2) Commands to gather system and Hardware information
dmidecode Command – Shows Linux Hardware Info
dmidecode –type processor
lshw Tool – List Hardware Configuration
lshw -C CPU
You may need additional packages to run the above commands.
yum install inxi
yum install cpuid
3) Networking commands.
# ifconfig eth0
Assigning IP Address and Gateway
# ifconfig eth0 192.168.0.10 netmask 255.255.255.0
Enable or Disable Specific Interface
# ifup eth0
Setting MTU Size
# ifconfig eth0 mtu <1234>
Set Interface in Promiscuous mode
# ifconfig eth0 – promisc
ARP Command,To view / add the contents of the kernel’s ARP tables.
test connectivity between two nodes
# ping -c 5 www.ranjeetbadhe.com
shows number of hops taken to reach destination
Netstat (Network Statistic) command display connection, routing table information
Dig (domain information groper) query DNS related information like A Record, CNAME, MX Record
#host -t CNAME www.ranjeetbadhe.com
Route command to display and manipulate ip routing table
#route add -net 126.96.36.199/24 gw 192.168.0.1
#route del -net 188.8.131.52/24 gw 192.168.0.1