Standard Linux Commands and Their Outputs

File Operations

• ls: List directory contents

  $ ls
  file1.txt  file2.txt  dir1/

• pwd: Print working directory

  $ pwd
  /home/user

Text Operations

• cat: Display file content

  $ cat file1.txt
  This is the content of file1.

• head: Display the beginning of a file

  $ head file1.txt
  First line of the file.

• tail: Display the end of a file

  $ tail file1.txt
  Last line of the file.

System Information

• uname -a: Display system information

  $ uname -a
  Linux hostname 5.4.0-42-generic #46-Ubuntu SMP Fri Jul 10 00:24:02 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

• free: Display memory usage

  $ free -h
            total        used        free      shared  buff/cache   available
  Mem:      7.7Gi       1.2Gi       5.8Gi       123Mi       717Mi       6.2Gi
  Swap:     2.0Gi          0B       2.0Gi

Networking

• ping: Test network connection

  $ ping -c 4 google.com
  PING google.com (172.217.22.14) 56(84) bytes of data.
  64 bytes from fra15s11-in-f14.1e100.net (172.217.22.14): icmp_seq=1 ttl=53 time=29.3 ms
  ...

`

Miscellaneous

• echo: Display a line of text
  bash
$ echo "Hello, World!"
Hello, World!


• history: Display command history
  bash
$ history
1 ls
2 cd ..
3 pwd
...