head

Linux head command is used to output the first 10 lines of a file. By default, when you head a file, it will list first 10 lines as the output, you can pass the options to output more number of lines which is listed below with great examples. 

DEFINITIONS

head - output the first part of files

USAGE

head [OPTION]... [FILE]...

DESCRIPTION

       Print the first 10 lines of each FILE to standard output.  With more
       than one FILE, precede each with a header giving the file name.

       With no FILE, or when FILE is -, read standard input.

       Mandatory arguments to long options are mandatory for short options
       too.

       -c, --bytes=[-]NUM
              print the first NUM bytes of each file; with the leading '-',
              print all but the last NUM bytes of each file

       -n, --lines=[-]NUM
              print the first NUM lines instead of the first 10; with the
              leading '-', print all but the last NUM lines of each file

       -q, --quiet, --silent
              never print headers giving file names

       -v, --verbose
              always print headers giving file names

       -z, --zero-terminated
              line delimiter is NUL, not newline

       --help display this help and exit

       --version
              output version information and exit

       NUM may have a multiplier suffix: b 512, kB 1000, K 1024, MB
       1000*1000, M 1024*1024, GB 1000*1000*1000, G 1024*1024*1024, and so
       on for T, P, E, Z, Y.  Binary prefixes can be used, too: KiB=K,
       MiB=M, and so on.

EXAMPLES

First 10 lines:

head dpkg.log command by default only list first 10 lines, even the file has 10000+ lines. 

root@letusstudy:/var/log# head dpkg.log
2020-04-01 06:50:47 startup archives unpack
2020-04-01 06:50:47 upgrade libquadmath0:amd64 8.3.0-26ubuntu1~18.04 8.4.0-1ubuntu1~18.04
2020-04-01 06:50:47 status triggers-pending libc-bin:amd64 2.27-3ubuntu1
2020-04-01 06:50:47 status half-configured libquadmath0:amd64 8.3.0-26ubuntu1~18.04
2020-04-01 06:50:47 status unpacked libquadmath0:amd64 8.3.0-26ubuntu1~18.04
2020-04-01 06:50:47 status half-installed libquadmath0:amd64 8.3.0-26ubuntu1~18.04
2020-04-01 06:50:47 status half-installed libquadmath0:amd64 8.3.0-26ubuntu1~18.04
2020-04-01 06:50:47 status unpacked libquadmath0:amd64 8.4.0-1ubuntu1~18.04
2020-04-01 06:50:47 status unpacked libquadmath0:amd64 8.4.0-1ubuntu1~18.04
2020-04-01 06:50:48 upgrade libitm1:amd64 8.3.0-26ubuntu1~18.04 8.4.0-1ubuntu1~18.04
root@letusstudy:/var/log#

First 15 lines: 

head -15 dpkg.log will list first 15 lines.

AUTHOR
Written by David MacKenzie and Jim Meyering.

REPORTING BUGS
GNU coreutils online help: <https://www.gnu.org/software/coreutils/>
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COPYRIGHT
Copyright © 2010 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.