How can I display the contents of a text file on the command line?

Using cat

Since your file is short, you can use cat.

cat filename

Using less

If you have to view the contents of a longer file, you can use a pager such as less.

less filename

You can make less behave like cat when invoked on small files and behave normally otherwise by passing it the -F and -X flags.

less -FX filename

I have an alias for less -FX. You can make one yourself like so:

alias aliasname='less -FX'

If you add the alias to your shell configuration, you can use it forever.

Using od

If your file contains strange or unprintable characters, you can use od to examine the characters. For example,

$ cat file
(ÐZ4 ?o=÷jï
$ od -c test
0000000 202 233   ( 320   K   j 357 024   J 017   h   Z   4 240   ?   o
0000020   = 367  \n
0000023

Even though everybody uses cat filename to print a files text to the standard output first purpose is concatenating. From cat's man page:

cat - concatenate files and print on the standard output

Now cat is fine for printing files but there are alternatives:

  echo "$(<filename)"
or
  printf "%s" "$(<filename)"

The ( ) return the value of an expression, in this case the content of filename which then is expanded by $ for echo or printf.

Update:

< filename

This does exactly what you want and is easy to remember.

Here is an example that lets you select a file in a menu and then prints it.

#!/bin/bash

select fname in *;
do
# Don't forget the "" around the second part, else newlines won't be printed
  printf "%s" "$(<$fname)"
  break
done

For further reading:
BashPitfalls - cat file | sed s/foo/bar/ > file
Bash Reference - Redirecting

Tools for handling text files on unix are basic, everyday-commands:

In unix and linux to print out whole content in file

cat filename.txt

or

more filename.txt

or

less filename.txt

For last few lines

tail filename.txt

For first few lines

head filename.txt