‘head’: Output the first part of files

‘head’ prints the first part (10 lines by default) of each FILE; it reads from standard input if no files are given or when given a FILE of ‘-‘.


  head [OPTION]… [FILE]…

If more than one FILE is specified, ‘head’ prints a one-line header consisting of:

==> FILE NAME <==

before the output for each FILE.

The program accepts the following options.

‘-c K’  | ‘–bytes=K’
     Print the first K bytes, instead of initial lines.  However, if K  starts with a ‘-‘, print all but the last K bytes of each file.  K
     may be, or may be an integer optionally followed by, one of the      following multiplicative suffixes:
          ‘b’  =>            512 (“blocks”)
          ‘KB’ =>           1000 (KiloBytes)
          ‘K’  =>           1024 (KibiBytes)
          ‘MB’ =>      1000*1000 (MegaBytes)
          ‘M’  =>      1024*1024 (MebiBytes)
          ‘GB’ => 1000*1000*1000 (GigaBytes)
          ‘G’  => 1024*1024*1024 (GibiBytes)

     and so on for ‘T’, ‘P’, ‘E’, ‘Z’, and ‘Y’.

‘-n K’ | ‘–lines=K’
     Output the first K lines.  However, if K starts with a ‘-‘, print all but the last K lines of each file.  Size multiplier suffixes
     are the same as with the ‘-c’ option.

‘-q’ |  ‘–quiet’  | ‘–silent’
     Never print file name headers.

‘-v’ | ‘–verbose’
     Always print file name headers.

For compatibility ‘head’ also supports an obsolete option syntax ‘-COUNTOPTIONS’, which is recognized only if it is specified first. COUNT is a decimal number optionally followed by a size letter (‘b’, ‘k’, ‘m’) as in ‘-c’, or ‘l’ to mean count by lines, or other option letters (‘cqv’).  Scripts intended for standard hosts should use ‘-c COUNT’ or ‘-n COUNT’ instead.

If your script must also run on hosts that support only the obsolete syntax, it is usually simpler to avoid ‘head’,

e.g., by using ‘sed 5q’ instead of ‘head -5’.

An exit status of zero indicates success, and a nonzero value indicates failure.



I have started unixadminschool.com ( aka gurkulindia.com) in 2009 as my own personal reference blog, and later sometime i have realized that my leanings might be helpful for other unixadmins if I manage my knowledge-base in more user friendly format. And the result is today's' unixadminschool.com. You can connect me at - https://www.linkedin.com/in/unixadminschool/

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