[File Management] cat

Definition:
  "cat" is a standard Unix utility that reads files sequentially, writing them to standard output. 
The name is derived from its function to concatenate files. 

Stands for:
  Concatenate
 
Function:
  Concatenate files and print on the standard output

Syntax: 
  cat [-benstuv][file ...]
 
Parameters:
  * "-n" or "--number": 
     Print out all the line numbers starting from 1;
  * "-b" or "--number-nonblank"
     Similar to "-n", but it does not numbering for blank line;
  * "-s" or "--squeeze-blank"
     Replace multiple continous blank lines (more than 2) as one blank line;
  * "-v" or "--show-nonprinting"
     Use ^ or M- simbol, except LFD and TAB;
  * "-E" or "--show-ends"
     Add $ at the end of each line;
  * "-T" or "--show-tabs"
     Show TAB as "^I";
  * "-A" or "--show-all"
     Equal to "-vET";
  * "-e"
     Equal to "-vE"
  * "-t"
     Equal to "-vT"

Examples:
  1) Print content of file "testfile1" with numbering into file "textfile2"
     "cat -n testfile1 > testfile2"
  2) Add content of file "testfile1" and "testfile2" with numbering (not for blank line) to file "testfile3"
     "cat -b testfile1 testfile2 ?? testfile 3"
  3) Empty the file of "etc/test.txt"
     "cat /dev/null > /etc/test.txt"


Reference:
1) Wikipedia
2) http://www.runoob.com/linux/linux-comm-cat.html