bash.md

1. Help
2. History
3. Several commands
4. if-else
5. loop
6. read file

Help

man bash

man builtin

# help on builtin command 'history'
help history

History

# show last N commands from bash history
history N

!!   repeat the previous line

# arguments
!*   all arguments
!:0  the command
!^   first argument
!$   last argument
!:N  N-th argument

!:2-4   2 to 4 arguments
!:2-$   2 to last arguments
!:2*    2 to last arguments
!:2-    2 to next to last arguments

Several commands

• A; B - run A and then run B, regardless of A failed or succeeded
• A && B - run A and if A succeeded then run B
• A || B - run A and if A failed then run B
• A & - run A in background
• (A ; B) - concatenate output of A and B
• (cd A ; ls -lh) - change directory to A and perform ls without changing directory