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



  • Text Processing Unix Commands

    Text processing Unix commands are those affecting text and text files. For example, commands like cut, paste, cmp, sort, comm, head, tail, wc, diff, grep are few in the list. While editing files, you may lose track of what changes you have made to which files.

    In this article, we will cover commands that compare files.

    cut command in Unix

      • Cut selected fields of each line of a file.
      • It can be used to cut parts of a line by byte position, character and field
      • It is necessary to specify option with command otherwise it gives error.
     
    SYNTAX:
    cut OPTION... [FILE]

    Option

    Use

    -b 

    Bytes, extract the specific bytes

    -c

    Characters, extract the specific characters

    -d

    Delimiter, use the mentioned delimiter

    -f

    Fields, extract only these fields

    Example:

    List without ranges:

    $ cat test.txt
    Learn Daily
    Study Smart
    Grow
    $ cut -b 1,2,3 test.txt
    Lea
    Stu
    Gro

    List with ranges:

    $ cut -b 1-3,5-7 test.txt
    Lean D
    Stuy S
    Gro

    Use -d option ,consider space as a field separator or delimiter:

    $ cut -d " " -f 1 test.txt
    Learn
    Study
    Grow

    paste command in Unix

      • Merging the corresponding lines of given files
      • It is used to join files horizontally (parallel merging)
    SYNTAX: 
    $ paste [Option] file1 file2

    Example:

    $cat file1.txt
    class
    Percent
    $cat file2.txt
    10th
    Pass
    $paste file1 file2 
    class  10th
    Percent Pass 
        • Display the top count lines of files or piped data to standard output.
        • It displays 10 lines by default
    SYNTAX:
    head [-count] [file ...] 

    Options

    Use

    -n

    “n” is number of lines

    -c

    “c” is number of bytes

    -f 

    Follow the change in the file

    -s

    Sleep interval

    Display Specific number of lines using head command

    the OPTIONS “-n” where n is an integer displays the specific number of lines of the file.

    SYNTAX:
    $ head -n <INTEGER> filename.txt
    or 
    $ head -<INTEGER> filename.txt

    Example:

    $ head -n 15 file1.txt
    $ head -15 file1.txt

    Display Specific number of bytes using head command

    the OPTIONS “-c” displays the specific number of bytes of the file.

    SYNTAX:
    $ head -c <INTEGER> filename.txt

    Example:

    $ head -c 150 file1.txt

    Display content of mutiple file using head command

    Head command displays first 10 lines (by default) of each file when multiple files are provided as input to it.

    SYNTAX:
    $ head filename1.txt filename2.txt

    to view a different number of lines use “-n” option.
    Example:

    $ head -n 15 file1.txt file2.txt
    text processing unix commands: Head and tai command in Unix

    tail command in Unix

      • Display the last count lines of files or piped data to standard output.
      • It displays 10 lines by default
    SYNTAX:
    tail [OPTIONS].. [FILE]..
    Options Use
      -n “n” is number of lines
    -c “c” is number of bytes
    -f  Follow the change in the file
    -s Sleep interval

    for more on options, refer here 

    Display Specific number of lines from last using tail command

    the OPTIONS “-n” where n is an integer displays the specific number of lines of the file.

    SYNTAX:
    $ tail -n <INTEGER> filename.txt
    or 
    $ tail -<INTEGER> filename.txt

    Example:

    $ tail -n 15 file1.txt
    $ tail -15 file1.txt

    Display Specific number of bytes from last using tail command

    the OPTIONS “-c” displays the specific number of bytes of the file.

    SYNTAX:
    $ tail -c <INTEGER> filename.txt

    Example:

    $ tail -c 150 file1.txt

    Display content of mutiple files

    Tail command displays last 10 lines (by default) of each file when multiple files are provided as input to it.

    SYNTAX:
    $ tail filename1.txt filename2.txt

    to view a different number of lines use “-n” option.
    Example:

    $ tail -n 15 file1.txt file2.txt

    Use tail with Other Commands in Unix

    The tail command can be used in combination with other commands in unix.

    Example:

    tail -f error.log | grep 'message'
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