awk is a domain-specific language and command for text processing available on Unix-compatible systems.
gawk is the GNU AWK and all Linux distributions come with it.
This is a brief tutorial for awk covering the most common use-cases.
awk reads input line by line from a file, pipe, or stdin and executes a program on each line.
An input line has a number of fields separated by white space or by regular expression FS.
The fields are denoted $1, $2, and so on and $0 denotes the entire line.
If FS is not set, the input line is split into one field per character.
awk <options> <program> <input_file>
Options
Here are some options for awk command that you most likely need to know about them.
| Option | Description |
|---|---|
-f | Specifies the file containing the awk program. |
-F | Specifies the regular expression for separating fields. |
Actions
An action is a sequence of statements.
| Action | Description |
|---|---|
print | Prints data on standard output. |
printf | Prints data on standard output. |
Examples
| Example | Description |
|---|---|
awk 'BEGIN {print "Hello, World!"}' | Prints Hello, World! on stdout. |
awk -F '\t' '{print $2, $4}' | Prints the second and fourth columns separated by tab. |