Some common linux commands are -

  • ls - show current files and directories
  • ls -l - show files and directories with permissions
  • cd - change directory
  • hostname - shows the host device name
  • ifconfig - display IP and MAC address
  • top - show all running processes
  • cat filename - shows the contents of the “filename”
  • mkdir - create directories
  • rm -rf dirname - removes directory and inside files. -r is for recursive and -f is for force.
  • history - see the history of all the commands.
  • ping host-ip - Check connectivity between hosts
  • chmod 777 filename - Assign read, write and execute permissions(rwx) to owner, group and others.
  • chmod -x filename - Remove execute functionality of file.
  • chown - change owner and group ownership of file
  • netstat -tulpn - check open ports which are listening of tcp and udp with their pid.
  • tcp dump port_number - check packets incoming and outgoing to the given port number
  • alias command to create a command alias such as alias lh="ls -lrth" and so later, when u do lh, it runs same as ls -lrth
  • brctl show -Shows information about the bridge network and veth interfaces it is connected to and its attached ports of veth pair in kubernetes
  • route- check the route table
  • ip addr - Displays the addresses for every link configured on the system, same as ip a
  • ip link sh - Inspect the network configuration within pod
  • ethtool -S eth0 or veth12abcd - query or control network driver and hardware settings with statistics flag
  • ip route sh - Show route table, same as route -n
  • ping ip - shows connectivity to the IP(cannot use port)
  • nc -vz ip_addr port - Checks tcp connectivity nc -vz 10.99.52.54 30080
  • traceroute - Shows route of packet flow traceroute ip
  • w or sudo w - check current logged in session for terminal
  • pv - monitor progress of a command execution pv file.tar.gz > /tmp/file.tar.gz
  • htop - see current cpu utilization
  • free -kh - see memory usage
  • du -sh - see disk utilisation

Git commands

git rev-parse --short HEAD - get the latest commitId

git remote -v - check repo which u are on

git branch - check current branch

git branch -r => remote branch use | wc -l to count branches

git checkout -b branchName - switch branches

git fetch - fetch all branches without merging anything Creating a local branch B from remote origin/B and checkout to it via - git checkout -b B origin/B then do git pull

git switch - For remote branches switch, you can run git switch branchName as well

Linux file permissions

User is the owner which creates the file. The user which creates is the owner by default. Group is group of multple users and all users of same group have same permissions alloted. Other is anyone who has access to file and is not owner and user.

We change owner of file using chown like chown owner_name filename.

Permissions are represented by numbers in following format -

  • 4 => read
  • 2 => write
  • 1 => execute

To give exact permission of read to all (user, group and others), command is chmod 444 filename The above method gives exact permission to file for all types of users.

For owner to have read and write (4+2), group to have execute(1) and other to have write and execute(2+1), the command is chmod 613 filename