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Hints and tips

Getting help about a command - man pages

Type,

$ man COMMAND

For example,

$ man ls
$ man grep
$ man git

The up and down arrows on your keyboard allow you to scroll up and down the page.

To exit from the man page, press q.

Auto-completion

Bash shells support what is called tab completion. If you type part of a command or file name, then press TAB, it will show the commands or files that match that prefix of the command. For example, if you type

$ gre

then, without pressing ENTER, you press TAB you should see something like

$ gre
greadelf  grep           grepjar
grefer    grep-changelog

which are all the commands that match gre. This also works for files. For example, if you type

$ ls dat

then, without pressing ENTER, you press TAB you should see a list of all the files that start with dat. If there is only one, then the file name will be auto-completed e.g.

$ ls data.txt

Command history, or avoid having to retype commands

Bash shells support a command history - they record every command you type in. If you use up-arrow, or CTRL-P, at the command prompt you can scroll back to the previous command you executed. Down-arrow, or CTRL-N, allows you to scroll to the next command.

You can then move the cursor and edit the command. To move the cursor in the line you can do,

  • Left, CTRL-B
  • Right, CTRL-F
  • To the start of the line, CTRL-A
  • To the end of the line, CTRL-E

If you enter,

$ history

You'll see a list of the commands in the history. Each has a number. If you enter,

$ !NNN

where NNN is the number of a command in the history, that command will be rerun.

To search for a command that you've run before you can do,

$ history | grep "COMMAND"

For example,

$ history | grep "ls"

A quick-start guide to the nano editor

nano is a simple text editor for Linux/Unix.

To start,

$ nano file.txt

To move the cursor,

  • Left, CTRL-B
  • Right, CTRL-F
  • Up a line, CTRL-P
  • Down a line, CTRL-N
  • To the start of the line, CTRL-A
  • To the end of the line, CTRL-E

To delete and undelete a line,

  • Delete the current line, CTRL-K
  • Undelete the recently deleted lines, CTRL-U

To save a file, CTRL-O. You will be given the opportunity to edit the file name to save the file under a different name.

To quit, CTRL-X. If the file has unsaved changes you'll be given the chance to save them now.

I don't recognise my prompt...where am I?

GNU nano is at the top of your window? You're in nano.

Your window looks like the following? You're in vi.

~
~
~    
~
"somefilename" ...

Something like somefilename (Fundamental) ---- is at the bottom of your window? You're in emacs or xemacs.

XEmacs: somefilename (Fundamental) ---- is at the bottom of your window? You're in xemacs.

Your prompt is >>> ? You're in python.

Your prompt is In [123]: ? You're in ipython.

--More--(...%) is at the bottom-left of your window? You're in more.

Manual page... is at the bottom-left of your window? You're in a man page.

: is at the bottom-left of your window? You're in less or a man page.

How do I exit from...

  • nano, type CTRL-X to exit. If you have unsaved changes, you will be asked to save these - press y to save, or n to quit without saving.
  • vi, type :q! to exit without saving. If the text just appears on screen then press ESC then type :q!
  • emacs or xemacs, CTRL-X CTRL-S. If you have unsaved changes, you will be asked to save these - press y to save, or n then type yes to quit without saving.
  • python, type exit() or CTRL-D
  • ipython, type exit(), or CTRL-D then press y
  • man page, press q
  • more or less, press q