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Command line, basics

Command line

The programs you call on a terminal are not so different from their graphical interface you are used to on windows/mac.

You need to know these commands:

pwd
more
less
cp
mv
mkdir
ls
cd
chmod
rm
find

Two useful tips:

  • use TAB on your keyboard for command and name completion.
  • the up arrow allows to browse your history (also available with history)

Exercise 1

go to your home folder
cd
create a fake file by using
echo "hello world" > filetest see if this file is present ls -l
read it
more fileTest
Of note, less is an alternative to more
rename it
mv fileTest test
check
ls -l
create a folder
mkdir TEST
Of note, all commands are case-sensitive ll
ll is a classic alias for ls -l move the file in this folder
mv test TEST
check, and see if present in the folder
ll TEST
copy it in the current folder
cp TEST/test .
. is the current folder, .. is the folder one level close to the root / now we have the same file, with the same name, one in the TEST folder, one in the current. use the up arrow, you should see 'cp TEST/test .' and change it for
cp TEST/test test2
the first and last field of ls -l should provide

drwxr-xr-x TEST
-rw-r--r-- test
-rw-r--r-- test2

trash test
rm test
if this command doesn't ask for confirmation, let me know we may change this behavior.

chmod allows changing permissions

try to read the file test after
chmod 222 test

r stands for read, w for write and x for execution for files and browsing for folders.
the first pattern is the owner
the second pattern is for the group
the third pattern is for everyone else

TODO more details needed

Text editor

nano

often installed, it is easy to use as all commands are written at the bottom:




^G Get Help                   ^O WriteOut                   ^R Read File                  ^Y Prev Page                  ^K Cut Text                   ^C Cur Pos
^X Exit                       ^J Justify                    ^W Where Is                   ^V Next Page                  ^U UnCut Text                 ^T To Spell

you can write/modify text directly and use CTRL + O to save then CTRL + X to exit.

VIM

Let's have a look at a text editor, there is plenty of them, the one I use is vim, why?

Because:

  • it's commonly installed on servers
  • extremely powerful

enter the editor
vim test2
you have two modes

  • command
  • insert

By default you are in the command mode, let's enter in the editor mode with either i or insert on your keyboard. You should see--INSERT-- at the bottom. Now you can edit your file. When its finished, press ECHAP to return in the command mode. You must enter : for each command. The useful ones

  • w save changes to the file
  • :q! quit without saving changes
  • :wq write and quit