Ark Linux (original) (raw)

'sed' for Search & Replace in Single or Multiple Files

sed stream editor - A Powerful Text Stream Editor

sed 'search-text'/replace-text'

$ sed -i 's/AnanovaSitegeek/g' /home/ananova/index.php

This command would open index.php and line-by-line would replace all the occurrences of Ananova with Sitegeek.

Search & Replace in Vim

'-i' in-pace edit, i.e., no need to redirect the output from sed to new file

'g' global replacement to replace all occurrences once per line
Replacing nth occurrence
Use the '/1', '/2' instead of '/g' flags to replace the first or second occurrence of the pattern in a line.
's,' to specify the range, when the scale is determined 'g' option omitted

$ sed '1,3 s/AnanovaSitegeek/g' /home/ananova/index.php

The sed command replaces the lines with a range from 1 to 3.

'%' for the entire document

'$' indicates last line in the file

$ sed '2,$ s/AnanovaSitegeek/g' /home/ananova/index.php

The sed command replaces the text from the second line to the last line in the file.

Esc Press Shitft : and provide the following command to provide one tab before line

:s/^/\t/

Parenthesize first character of each provide provided as on output of echo command through the pipe:

echo "Web Hosting Industry Demystified" | sed 's/\(\b[A-Z]\)/\(\1\)/g'

(W)eb (H)osting (I)ndustry (D)emystified

To replace the string on a specific line number

$ sed '3 s/AnanovaSitegeek/g' /home/ananova/index.php

The above sed command replaces the string only on the third line.

Deleting Lines from File

Delete the last line

$ sed '$d' index.php

Delete a particular line say n

$ sed 'nd' index.php

$ sed '3d' filename.txt

Delete line from range x to y

$ sed 'x,yd' index.php

$ sed '12,15d' index.php

Delete from nth to the last line

$ sed 'nth,$d' index.php

$ sed '10,$d' filename.txt

Delete pattern matching line

$ sed '/pattern/d' index.php

$ sed '/flowentry/d' index.php

World of Text Editing with Vi & Vim

'vi' written in 1976, become the part of BSD UNIX in 1978. According to the Linux Journal survey, even without GUI, it is the most popular editor, and GUI GNOME editor comes second. The reason behind its popularity is its permissiveness, convenience, performance, and speed.

Vim (vi Improved) released in 1991 by Bram Moolenaar, targeting Amiga systems. It is distributed as a vim-enhanced package with GUI frontend. The most notable improvement over 'vi' is its syntax highlighting feature for languages such as PHP, PERL, and PYTHON.

$ alias | grep vi alias vi='vim'

Vim needs 'vim-XII' package for the graphical interface. You can install it with the following command:

$yum install vim-XII

Edit file using vi or vim

$vi

$gvim

$vimx -g (without -g option it starts normal vim program)

Control Functionalities & Customize Appearance

/etc/vimrc for all users i.e., system-wide settings

~/.vimrc for each user

By Default Values in /etc/vimrc

if v:lang =~ "utf8$" || v:lang =~ "UTF-8$"
set fileencodings=ucs-bom,utf-8,latin1
endif

set nocompatible " Use Vim defaults (much better!)
set bs=indent,eol,start " allow backspacing over everything in insert mode
"set ai " always set autoindenting on
"set backup " keep a backup file
set viminfo='20,\"50 " read/write a .viminfo file, don't store more
" than 50 lines of registers
set history=50 " keep 50 lines of command line history
set ruler " show the cursor position all the time

" Only do this part when compiled with support for autocommands
if has("autocmd")
augroup redhat
autocmd!
" In text files, always limit the width of text to 78 characters
" autocmd BufRead *.txt set tw=78
" When editing a file, always jump to the last cursor position
autocmd BufReadPost *
\ if line("'\"") > 0 && line ("'\"") <= line("$") |
\ exe "normal! g'\"" |
\ endif
" don't write swapfile on most commonly used directories for NFS mounts or USB sticks
autocmd BufNewFile,BufReadPre /media/*,/run/media/*,/mnt/* set directory=~/tmp,/var/tmp,/tmp
" start with spec file template
autocmd BufNewFile *.spec 0r /usr/share/vim/vimfiles/template.spec
augroup END
endif

if has("cscope") && filereadable("/usr/bin/cscope")
set csprg=/usr/bin/cscope
set csto=0

set cst

set nocsverb

" add any database in current directory

if filereadable("cscope.out")

cs add $PWD/cscope.out

" else add database pointed to by environment

elseif $CSCOPE_DB != ""

cs add $CSCOPE_DB

endif

set csverb

endif

" Switch syntax highlighting on, when the terminal has colors

" Also switch on highlighting the last used search pattern.

if &t_Co > 2 || has("gui_running")

syntax on

set hlsearch

endif

filetype plugin on

if &term=="xterm"

set t_Co=8

set t_Sb=^[[4%dm

set t_Sf=^[[3%dm

endif

" Don't wake up system with blinking cursor:

" http://www.linuxpowertop.org/known.php

let &guicursor = &guicursor . ",a:blinkon0"

Turn Line Numbering ON/OFF

To enable line numbering add the following command in a file:

vi ~/.vimrc

set number

and to set line numbering off

set nonumber

Turn Off Argument Highlighting

You can provide search arguments to vi, and it will take directly to the first appearance of the word in the file or on a particular line number.

vi +55 index.php

vi +/copyright index.php

The word searched is highlighted in color, if not desirable, can be turned off by adding:

set nohlsearch

Toggle Line Numbering ON/OFF

Navigate to particular line number by typing:

G

or

gg

Like 3G or 3gg to navigate to line number 3. If we don't wish to provide 'G' and with to reach directly to a line by providing line number, followed by 'Enter' key, then type the following line in ~/.vimrc file.

nmap G

We provide a command

vi +235 index.php

to reach that 235 line number. Press Shift g to reach the end of file and gg to the first line of the file.

Linux Trickery Shortcuts

Double pipe || between two commands - if the first command fails, then second will execute.

||

Double && between two commands - the second command would run only when first succeeds.

&&

Example:

cd joininternet || mkdir joininternet && cd joininternet

The above command changes directory to join-internet, and suppose if does directory does not exists, then the command would fail, but as we have provided another after ||, then the second would execute and create the directory join-internet. After that, as change directory command is also given after &&, it would also get completed. Finally, we reach to directory join-internet.

Command History - If we press up arrow keyboard key, the lastest command executed in the history gets displayed.

Last command argument with !$

mkdir join-internet

cd !$ Here, i$ = join-internet

cd join-internet || mkdir !$ && cd !$

!v would look in the history for a command which starts with letter 'v'. Similarly, if we provide !?75, it would look for 75, anywhere as an argument or its part.

date --date "75 days ago"

Linux the topmost choice of business organizations

Linux is authoritative and accessible as it is dependable, reliable, and resilient. It has a vast community which takes ownership to Linux distributions and helps to develop services, applications and provide remedies to bugs.

Linux Enterprise Disributions

Cent OS (Communition Enterprise Operating System)
https://wiki.centos.org/Download
It's free and open to use under the terms of GPL license.

Red Hat, Debian, SUSE Enterprise

Home or Enthusiast-oriented Distributions

Fedora, Open SUSE

Benefits

Important for Administrators

Change the Port of the server

vi /etc/ssh/sshd_config

change #Port 22

to Port 8022

/etc/init.d/sshd restart

Creating Domain Entry

vi /etc/named.conf

cd /var/named/

Checking Error Logs

tail -f /usr/local/apache/logs/error_log

Business Web Hosting on Dedicated Servers

Most branded businesses opt for a dedicated server or cloud hosting for their website.

Why dedicated-Server?

Discounts

Most companies offer attractive discounts when payment mode is quarterly, half-yearly, or annually. The businesses choose a monthly way, as they don't want to be stuck for more extended periods.

Dedicated Server Customers

Benefits Over

Shared Hosting

Free Server

Drawbacks

Costliest: cost run a couple of hundred dollars

Find the best-dedicated server providers on Ananova, where quality companies listed with the monthly rate, space, and bandwidth they are offering.