How to print or concatenate files in linux with cat command? (Advanced)
cat is one basic and most used command by Linux users. It simply prints the contents of a file or STDIN as output on the terminal. But that is not the full power of cat command. There are many advanced uses of cat which are rarely known.
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Based syntax of cat command:
cat [OPTION]... [FILE]...
Description of options available in cat command:
| Options |
Descriptions |
-A, --show-all |
equivalent to -vET |
-b, --number-nonblank |
number non-empty output lines, overrides -n |
-e |
equivalent to -vE |
-E, --show-ends |
display $ at end of each line |
-n, --number |
number all output lines |
-s, --squeeze-blank |
suppress repeated empty output lines |
-t |
equivalent to -vT |
-T, --show-tabs |
display TAB characters as ^I |
-v, --show-nonprinting |
use ^ and M- notation, except for LFD and TAB |
Show line number with cat command in Linux
To display line numbers in front of each line with cat command we use the -n (--number) option.
Syntax: cat -n <fileName>
To display line numbers in front of each non-empty line with cat command we use the -b (--number-nonblank) option.
Syntax: cat -b <filename> or cat -n -b <filename>
Show all characters with cat command in Linux
To display non-printable characters with cat command we have the following options: -A, -v, -E, -T.
Non-printable characters are parts of a character set that do not represent a written symbol or part of the text within a file or code. These characters tells a program like cat about how a document is supposed to look.
1. Show end character at the end of each line with cat command in Linux
To display $ after the last character of each line with cat command we use the -e (--show-ends) option.
Syntax: cat -E <filename>
2. Show TAB character with cat command in Linux
To display TAB characters as ^I with cat command use the -T (--show-tabs) option.
Syntax: cat -T <filename>
3. Show non-printing characters with cat command in Linux
To display Non-printable characters which use ^ and M- notation, except for LFD and TAB (e.g. color deciding characters) use -v (--show-nonprinting) option.
Syntax: cat -v <filename>
Tip: -A is equivalent to -vET and -t is equivalent to -vT and -e is equivalent to -vE.
Remove repeated empty lines with cat command in Linux
To suppress annoying repeated empty lines with cat command with -s (--squeeze-blank)option.
Syntax: cat -s <filename>
Conclusion
In this tutorial, you have learned some advanced usage of cat command. To show line numbers, non-printable characters and squeeze unwanted empty lines.
