Editing at the Command line

Common key combinations:

• Ctrl+a / Home
  • Moves the cursor to the beginning of the command line
• Ctrl+e / End
  • Moves the cursor to the end of the command line
• Ctrl+u
  • Erase everything at and before cursor
• Ctrl+k
  • Erase Everything at cursor and after
• Alt+f
  • Moves the cursor to the right one word at a time
• Alt+b
  • Moves the cursor to the left one word at a time
• Ctrl+f / Right arrow
  • Moves the cursor to the right one character at a time
• Ctrl+b / Left arrow
  • Moves the cursor to the left one character at a time

Tab completion

• Hitting the Tab key twice automatically completes the entire name.
• In case of multiple possibilities matching the entered characters, it completes up to the point they have in common and prints the rest of the possibilities on the screen.

Tilde Substitution (tilde expansion)

• Performed on words that begin with the tilde character (~). ~
  • refers to user’s home directory.

~+ - refers to current directory

~- - Refers to previous working directory.

~USER - Refers to specific user’s home directory.

Alias Substitution (command aliasing or alias)

• Define shortcuts for commands.
• Bash shell includes several predefined aliases that are set during user login.
• Shell gives precedent to an alias if an alias matches a command or program.
  • can still run the command without using the alias but preceding command with a backslash. \

alias command

• Set an alias.
• Internal shell command.

[root@localhost ~]# alias
alias cp='cp -i'
alias egrep='egrep --color=auto'
alias fgrep='fgrep --color=auto'
alias grep='grep --color=auto'
alias l.='ls -d .* --color=auto'
alias ll='ls -l --color=auto'
alias ls='ls --color=auto'
alias mv='mv -i'
alias rm='rm -i'
alias xzegrep='xzegrep --color=auto'
alias xzfgrep='xzfgrep --color=auto'
alias xzgrep='xzgrep --color=auto'
alias zegrep='zegrep --color=auto'
alias zfgrep='zfgrep --color=auto'
alias zgrep='zgrep --color=auto'

[root@localhost ~]# alias frog='pwd'
[root@localhost ~]# frog
/root

unalias command

• Unset an alias.
• Internal shell command.

[root@localhost ~]# unalias frog
[root@localhost ~]# frog
-bash: frog: command not found