There are several commands that display information about a file in the read-only format. The file-viewing commands include the following:
- cat
- more
- tail
- head
- wc
cat Command
The cat command displays the content of one or more text files on the screen without pausing.
$ cat filename
For Example:
# cat data.txt northwest NW Joel Craig 10 western WE Sharon Kelly 40 southwest SW Chris Foster 33 central CT Sheri Watson 44
Do not use the cat command to read binary files. Using the cat command to read binary files can cause a terminal window to freeze. If your terminal window freezes, close the terminal window, and open a new terminal window.
more Command
The more command displays the content of a text file one screen at a time.
$ more filename
The
--More--(n%)
message appears at the bottom of each screen, where n% is the percentage of the file that has been displayed. When the entire file has been displayed, the shell prompt appears.
When the –More–(n%)prompt appears at the bottom of the screen, you can use the keys described in the table to scroll through the file.
| Keyboard Command | Action |
|---|---|
| Space bar | Moves forward one screen |
| Return | Scrolls one line at a time |
| b | Moves back one screen |
| h | Displays a help menu of features |
| /string | Searches forward for pattern |
| n | Finds the next occurrence of pattern |
| q | Quits and returns to the shell prompt |
head Command
The head command displays the first 10 lines of a file.
$ head -n filename
You can change the number of lines displayed by using the -n option. For example, to display the first five lines of the /var/log/messages file, enter the head command with the -n option set to 5.
$ head -5 /var/log/messages
tail Command
The tail command displays the last 10 lines of a file.
$ tail –n/+n filename
You can change the number of lines displayed by using the -n or +n options.
– The -n option displays n lines from the end of the file.
– The +n option displays the file from line n to the end of the file.
For example, to display the last four lines of the /var/log/messages file, enter the tail command with the -n option set to 4.
$ tail -4 /usr/dict/words
For example, to display line 10 through the end of the data.txt file, enter the tail command with the +n option set to 10.
$ tail +10 data.txt
wc Command
The wc command displays the number of lines, words, and characters contained in a file.
$ wc -options filename
You can use the following options with the wc command.
| Symbol | Description |
|---|---|
| -l | Line count |
| -w | Word count |
| -c | Byte count |
| -m | Character count |
When you use the wc command without options, the output displays the number of lines, words, and characters contained in the file. For example, to display the number of lines, words, and characters in the dante file, use the wc command.
$ wc data.txt 32 223 1319 data.txt
For example, to display the number of lines in the dante file, enter the wc command with the -l option.
$ wc -l data.txt 32 data.txt