Tutorials Hut

Tutorials Hut

  • Unix For Testers

       Introduction to Unix
       Unix System Architecture
       Unix File System Structure
       Absolute and Relative Path
       Basic Unix Commands
       cal command in Unix
       who command in Unix
       date command in Unix
       clear command in Unix
       more command in Unix
       whoami command in Unix
       uname command in Unix
       man command in Unix
       echo command in Unix
       Unix File System Commands
       ls command in Unix
       cat command in Unix
       cp command in Unix
       mv command in Unix
       pwd command in Unix
       cd command in Unix
       mkdir command in Unix
       rmdir command in Unix
       rm command in Unix
       touch command in Unix
       dirname command in Unix
       tar command in Unix
       Unix Links(ln)
       Hard Link
       Soft Link
       Regular Expressions
        Basic Regular Expressions
       Interval Regular Expressions
       Pipes and Filters
       Unix Text Processing Commands
       cmp command in Unix
       diff command in Unix
       comm command in Unix
       cut command in Unix
       Paste command in Unix
       head command in Unix
       tail command in Unix
       wc command in Unix
       sort command in Unix
       grep command in Unix
       Process Related Command
       top command in Unix
       ps command in Unix
       nice command in Unix
       Kill command in Unix
       nohup command in Unix
       time command in Unix
       File Tranfer Commands in Unix
       file transfer using scp command
       file transfer using rlogin command
       file transfer using telnet command
       ssh(Secure Shell) command in Unix
       ftp file transfer command
       sftp file transfer command
       chmod command in Unix
       File Permission and File Security in Unix



  • Pipes and Filters in Unix / Linux

    Pipes and filters  in Unix are the set of commands that take input from standard input stream i.e. stdin, perform some operations and write output to standard output stream i.e. stdout.

    In this article, we will cover below topics:

    Pipes in Unix

    Redirecting input/output to a named file, two commands can be connected together so that the output from one program becomes the input of the next program using pipe. When a pipe is established between two commands, the output of first command is redirected to standard input of second command. You can achieve this by using a vertical bar (|) on the command line between two commands represents pipe.

    SYNTAX:
    $command 1|command 2

    Filters in Unix

    Any program that can take input from standard input and write results to standard output (after processing) is called filter.

    The stdin and stdout can be managed as per preferences using redirection and pipes. Common filter commands are: grep, sort , more etc.

    Pipes and filters in Unix
      1. grep

    It is a pattern or expression searching command. 

    Prints found matches.

    Syntax:
    $grep[options] "pattern to be matched" [filename ]

    Example:

    $grep 'hello' testFile.txt

    Output : searches hello in the testFile.txt and outputs/returns the lines containing ‘hello’.

    Grep command can also be used with meta-characters:

    Example:

    $grep 'test' *

    Output : it searches for ‘test’ in all the files and directories.

    * is a meta-character and returns matching 0 or more preceding characters

    refer here for more examples on grep command.

      1. sort 

      • Ordered arrangement.
      • sorts lines of text alphabetically or numerically, default sorting is alphabetical
    SYNTAX:
    $sort[options] filename

    OPTION     USE 

    -d  :               dictionary order sort
     -n :               arithmetic/numeric order
     -r :                reverse order
    -k :                n Sorts on field n
    -b :                ignore leading blanks
    -m:               Merge (not sort)

    Example:

    $sort file1.txt
    $sort -n file2.txt
      1. more 

      • customize the display  content of the file. 
      • It displays the text file contents on the terminal with paging controls. 

    You can use below key controls with more command:

      • You can display next line by pressing the enter key
      • To bring up next screen, press spacebar
      • If you want to move to the next file, press n
      • To quit, press q.
    SYNTAX:
    $more[options] filename

    Example:

    $cat file1.txt | more

     After executing above command, more command is displayed at the bottom of the screen. Use keyboard inputs  to move through the text.

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