Basic Linux Commands

Browse the directory structure

pwd	tell you where you are
ls	list the content of the current directory
ls <directory>	list the content of a directory
cd <directory>	go to the specified directory
cd ~ (or cd)	go to your home directory
cd ..	go to the parent directory
tree <directory>	list the content of a directory in a tree-like format
mkdir <directory>	create the specified directory

less, more	view text with paging
head	print first lines of a file
tail	print last lines of a file
cat	print the content of a file to the screen
zcat	print the content of a `gzip` compressed file to the screen

find <folder>/ -type f	recursively find all files in a specific folder
find . -name '<pattern>'	recursively find anything whose name contains <pattern> in the current folder (Single quotes must be used in order to avoid wildcard expansion by the shell)
grep <pattern>	show lines of text containing a given pattern
grep -v <pattern>	show lines of text not containing a given pattern
sort	sort lines of text files
wc	count words, lines and characters
> (output redirection)	allow to redirect the output to a file
\| (pipe)	allow to send the output from one program to another
cut	extract selected portion of each line from one or more files
echo	input a line of text and display it on standard output

AWK - UNIX shell programming language. A fast and stable tool for processing text files.

awk '/www/ { print $0 }' <file>	search for the pattern `www` in each line of the file
awk '$3=="www"' <file>	search for the exact match of `www` in the third column of the file
awk 'length($0) > 80' <file>	print every line in the file that is longer than 80 characters
awk 'NR % 2 == 0' <file>	print even-numbered lines of the file

NR	Number of records
NF	Number of fields
FS	Field separator character
OFS	Output field separator character

Note	See http://www.grymoire.com/Unix/Awk.html and http://www.tutorialspoint.com/awk/awk_basic_examples.htm for more information