====== Linux commands ======
===== Global commands =====
==== Uso de servidores ====

<code>
# Mirar el espacio en disco
$ df -h
# Mirar el espacio en memoria
$ free -h
# Mirar la ip
$ ip address
</code>

==== Comprimir y descomprimir ====
<code>
tar -zcvf archive-name.tar.gz directory-name
# Extract
tar -zxvf prog-1-jan-2005.tar.gz
# Extract in a particular directory
tar -zxvf prog-1-jan-2005.tar.gz -C /tmp
</code>

====== Commands ======
===== alias =====
<code>
alias emacs="emacs -nw"
</code>
===== apt =====

=== Install ===
''apt install <package>''

=== Reinstall ===
''sudo apt-get install opera-stable --reinstall''

=== Remove ===
''sudo apt-get purge opera-stable''

=== Get the source code ===
''sudo apt-get source opera-stable''

=== Listar paquetes ===
''apt-cache search keyword''

''apt-cache search .''

=== Listar paquetes instalables, upgradables... ===

''apt list --<param> <?package>'', param=(installed|upgradeable|all-versions)

=== Listar versiones de un paquete ===

''apt-cache policiy <package>''

=== Ver información concreta de un paquete ===
''sudo apt-cache show "opera-stable"''

=== Instalar una versión concreta ===

''apt install <package>=<version>''

=== Update or upgrade ===

You just need to do ''apt-get install --only-upgrade <packagename>''. This will upgrade only that single package, and only if it is installed. If you wish to install the package if it doesn't exist, or upgrade it if it does, you may leave out ''--only-upgrade''.

==== Set a proxy ====

Edit apt-conf file (or create a new one if you have no one yet) using the editor of your choice.
<code>
sudo nano /etc/apt/apt.conf
</code>
Add this line to your /etc/apt/apt.conf file (substitute your details for yourproxyaddress and proxyport).
<code>
Acquire::http::Proxy "http://yourproxyaddress:proxyport";
</code>
===== ls =====
  * Order ls: ''ls -t''
  * For reverse order (most recent at bottom): ''ls -tr''

===== df =====
Disk usage.

  * In MB: ''df -m''
  * In a human readable format: ''df -h''

===== chown =====
Change the owner:
  * For changing the user and the group recursively: ''chown www-data: -R .'' 

===== findmnt =====
To display mounted data:
<code>
findmnt
</code>
Other options:
<code>
# List format
findmnt -l
# Showing disk usage
findmnt –D
# fstab
findmnt -s
# filter by type:
findmnt -t ext4
findmnt -t xfs
# filter by device:
findmnt -S /dev/vda3
# filter by mounted point:
findmnt -T /
</code>
===== tail =====
To see the last lines of a file.
  * For maintaining it reading it use ''-f'' parameter.


===== tree =====
To see a tree of only directories until 3rd level:

<code>
tree -d -L 3
</code>

The next will also give you the disk space used:
<code>
tree --du -h
</code>
===== xargs =====
To send output as parameters:
<code>
$ echo 'one two three' | xargs mkdir
$ ls
one two three
</code>

**Script example** for creating .cbz files from folders inside the current path:
<code>
ls -1 | xargs -I {} zip {}.cbz -r {}
</code>
===== Zip and unzip =====
<code>
zip -r app.old.zip app/
</code>
===== Others =====

  * htop -> easy to use top command
  * glances -> easy to use monitoring command
  * tree -> to show the folder tree
  * watch -> wait showing a command output
  * shutdown now -> turn the computer off
  * i3lock -c 000000 -> turn the screen off
  * xdotool -> for sending via command line keys, texts... to the GUI
==== Tips for commands ====

**!<command>** will execute the <command> with the parameters you executed last time:  remember the command name e.g. !ls will execute your last “ls -lrt” , !vim will open your last file without typing full command.

**!!** will execute the last command.
====== Move on the paths ======

''cd -'' goes to the prev visited path.

''pushd'' and ''popd'' create a stack of path. If you arrive to a path and want to add it on the stack, you will do ''pushd .''

With ''dirs'' command you can see the stack.

You can add this to .bashsrc to add ''cd +'' as ot do ''popd''. So when you visit a path you auto add pushd's:
<code>
cd()
{
  if [ $# -eq 0 ]; then
    pushd "$HOME" > /dev/null
  elif [ $1 = "+" ]; then
  	popd > /dev/null
  else
    pushd "$@" > /dev/null
  fi
}
</code>

====== Others ======
===== Close others sessions =====
:!: It's not recommended to do this for root; it could close all the current running processes.
<code>
pkill -KILL -u user
</code>
===== Create cbz from folders =====
<code>
ls -1 $* | xargs -I {} zip "{}.cbz" -r "{}"
</code>
===== Clear and reset =====
You can do ''Ctrl+l'' to clear the screen which is the same than ''clear'' command.

To actually reset the scroll and everything you will use the ''reset'' command.

===== Useful aliases =====
<code>
My favorite new one that I have been using a lot:
  function cheat() {
      curl cht.sh/$1
  }
It queries the cht.sh cheatsheet of various Unix commands. 'cheat tar' prints:
  # To extract an uncompressed archive:
  tar -xvf /path/to/foo.tar
  
  # To create an uncompressed archive:
  tar -cvf /path/to/foo.tar /path/to/foo/
  
  # To extract a .gz archive:
  tar -xzvf /path/to/foo.tgz
  
  # To create a .gz archive:
  tar -czvf /path/to/foo.tgz /path/to/foo/
  ...
</code>