100 Useful Command-Line Utilities

by Oliver; 2014

13. head, tail

Based off of An Introduction to the Command-Line (on Unix-like systems) - head and tail: head and tail print the first or last n lines of a file, where n is 10 by default. For example:

$ head myfile.txt      # print the first 10 lines of the file
$ head -1 myfile.txt   # print the first line of the file
$ head -50 myfile.txt  # print the first 50 lines of the file

$ tail myfile.txt      # print the last 10 lines of the file
$ tail -1 myfile.txt   # print the last line of the file
$ tail -50 myfile.txt  # print the last 50 lines of the file

These are great alternatives to cat, because often you don't want to spew out a giant file. You only want to peek at it to see the formatting, get a sense of how it looks, or hone in on some specific portion.

If you combine head and tail together in the same command chain, you can get a specific row of your file by row number. For example, print row 37:

$ cat -n file.txt | head -37 | tail -1  # print row 37

Another thing I like to do with head is look at multiple files simultaneously. Whereas cat concatencates files together, as in:

$ cat hello.txt
hello
hello
hello

$ cat kitty.txt 
kitty
kitty
kitty

$ cat hello.txt kitty.txt 
hello
hello
hello
kitty
kitty
kitty

head will print out the file names when it takes multiple arguments, as in:

$ head -2 hello.txt kitty.txt 
==> hello.txt <==
hello
hello

==> kitty.txt <==
kitty
kitty

which is useful if you're previewing many files. To preview all files in the current directory:

$ head *

See the last 10 lines of your bash history:

$ history | tail        # show the last 10 lines of history

See the first 10 elements in the cwd:

$ ls | head

<PREV   NEXT>