gnu/linux

Clean up the GNU/Linux console

If your console (terminal) is in a state where you don't see what you write because of an aborted ssh session or it is showing unreadable characters after trying to open a binary, this can be solved by typing the command:

14 Practical examples of the grep command

grep is a command-line utility that allows searching of words and/or patterns in a file or group of files. Its name comes from the ed command g/re/p (globally search a regular expression and print). Grep does a global search by keyword or regular expression and print all matching lines on the standard output.

Exclude the process grep on ps ax output

Regularly I use ps ax | grep pattern to get information about a particular process, but in the oupout the grep process is shown, how to avoid this?

Simply encloses within square brackets the first letter or number of the pattern, for example:

VIM case sentive / insensitive search

VIM

How to make VIM insensitive to uppercase and lowercase letters in a search?

Vim by default is case sensitive but this behavior can be modified through the options: ignorecase, ic, noignorecase, noic or adding c to the search pattern

Note: If you are in insert mode you must press Esc to switch to Normal mode

Case insentive temporarily

:set ignorecase

O

:set ic

Case sensitive

:set noignorecase

O

:set noic

Using c

/category\c

Find all words that contain category regardless of uppercase and lowercase letters

Case insensitive permanently

Edit the file /etc/vimrc (global) or ~/.vimrc (at the level of user) and add:

set ic

O

set ignorecase

Further reading

  • man vim
  • :help 'ignorecase', :help ignorecase

Kill GNU/Linux process from the command line

Desktop like GNOME, KDE, XFCE, LXDE have a task manager that allows you to terminate a process using the graphical interface, but not always we have managers like these or we simply work without graphical interface (server) and we need to kill a particular process because it does not respond to any action, and that's when should lend hands to the console

Remote commands on GNU/Linux

To run a remote command on GNU/Linux or another UNIX variant, you must be able to access the remote server through ssh

In order to run the remote command type:
$ ssh servidor-remoto command

Nano: lightweight and flexible text editor

Nano, improved version of Pico, is a friendly, lightweight and flexible text editor, it is ideal to make simple edits. Nano is a modeless text editor (no need to run any command or key combination to start editing the selected file). Once started it shows in the first line: the current version, the name of the file being edited and whether it has been modified or not; then the file in question, in the third line from the bottom up the important messages and in the last 2 lines the most common shortcuts, see figure. The main keys for Nano are: Ctrl (^) and Esc (M), ie with Esc or Ctrl and another key combination we can execute an action. Within its essential features we can mention:

  • Clean interface
  • Low learning curve
  • Internationalization
  • Syntax highlighting for C, C++, Python, Perl, Ruby, HTML, TeX and other
  • Searches / replacement by keywords or regular expressions
  • Forward / back one screen
  • File Explorer
  • Edit multiple files
  • Mouse support
  • Help integrated into the editor
[caption id="attachment_2937" align="aligncenter" width="911"]nano flexible and lightweight text editor nano flexible and lightweight text editor[/caption]

Edition

General syntax

nano [OPCIONES] [+LINE,COLUMN] file

Open the apache2.conf file and go to 20 line, column 23

nano +20,23 /etc/apache2/apache2.conf 

Edit file1.txt

nano file1.txt

Make relevant modifications and

Save the changes

Ctrl o

Nano it will request confirmation on the file that you want to modify, press:

Enter

Copy the current line and store it in the buffer

Esc 6

Cut the current line and store it in the buffer

Ctrl k

Paste what is in the buffer

Ctrl u

Use the mouse to select various lines

Esc a

To copy / cut / paste the selected lines use

Esc 6/Ctrl k/Ctrl u

respectively

Movement

Go to the first line of the file

Esc \

Go to the last line of the file

Esc /

Go to line 10, column 20

Esc g

Nano will request the line and column number to which you want to go, type:

10,20

Go to the beginning of the current line

Ctrl a

Go to the end of the current line

Ctrl e

Moving to matching braces

Esc ]

Advance one screen

Ctrl v

Go back one screen

Ctrl y

Advanced options

Search by keywords

Ctrl w

Search using regular expressions

Ctrl w Esc r

Repeat last search

Esc w

Enable / disable the mouse support

Esc m

Launch integrated help

Ctrl g

Further reading

Shell script to rename to lowercase files and directories

GNU/Linux

In the GNU/Linux world, it is common to use lowercase characters to identify files and directories, to illustrate the above we show the DIRs that are found under the /etc/apache2 DIR on Debian GNU/Linux

/etc/apache2/
├── conf-available
├── conf-enabled
├── mods-available
├── mods-enabled
├── sites-available
└── sites-enabled

so if you have one or several DIRs in uppercase or lowercase and uppercase at the same time and for uniformity want to all be lowercase then you can rely on the following script.

[githubget repo=1]sysadmin/shscript/tolower.sh[/githubget]

To use the script download here

Set execute permissions
chmod a+x tolower.sh
Run the script
./tolower.sh nombre-del-fichero

Further readings

  • man find
  • man tr