gawk Command in Linux
gawk is a command used in Linux that allows you to perform text processing and data manipulation. Its a GNU version of the gawk programming language that you can use to scan and process patterns on your system.
By using gawk command, you can search patterns within text files and perform actions on the matching lines. It allows you to use variables, string functions, arithmetic operations and logical operators. Its a pretty handy tool that can be used to perform tasks like generating reports, transforming data files and formatting output.
Table of Contents
Here is a comprehensive guide to the options available with the gawk command in linux −
- How to Install gawk Command in Linux?
- Syntax of gawk Command
- gawk Command Options
- Examples of gawk Command in Linux
How to Install gawk Command in Linux?
By default, gawk utility doesnt come preinstalled on any Linux system, but you can manually install it directly from your default systems repository.
On Linux systems like Ubuntu, Debian and other such systems that uses APT package manager, you can simply run the following command to install gawk −
sudo apt install gawk
For systems using the YUM or DNF package managers, such as Red Hat, CentOS, and Fedora, you can install gawk with the following commands −
sudo yum install gawk
Or,
sudo dnf install gawk
For Arch Linux, you can use the Pacman package manager to install gawk −
sudo pacman -S gawk
For OpenSUSE systems, use the Zypper package manager to install gawk −
sudo zypper install gawk
The above command will download and install the gawk package along with its dependencies, and ensure that the utility is ready for use on your system.
Syntax of gawk Command
The basic syntax to use the gawk command on Linux is as follows −
gawk [options] 'program' file
Here,
- gawk is the command itself.
- [options] are optional flags that modify the behavior of gawk.
- 'program' is the gawk program or script, usually enclosed in single quotes.
- file is the input file to be processed.
gawk Command Options
There are a large number of options you can use with the gawk command, these are described in the table below −
| Option | Description |
|---|---|
| -b, --character-as-bytes | Handles all input data as single-byte characters. |
| -c, --traditional | Enables traditional awk compatibility mode. |
| -C, --copyright | Displays the abbreviated GNU copyright information on the standard output and exits successfully. |
| -d[file], --dump-variables[=file] | Generate a sorted list of global variables, including their types and final values. |
| -D[file], --debug[=file] | Enables debugging mode. |
| -e program-text, --source program-text | Enables specifying the awk program directly on the command line. |
| -E file, --exec file | Reads the awk program from a file and exits after processing it. |
| -F fs, --field-separator fs | Defines the field separator as fs |
| -f file, --file file | Loads the awk program from a file rather than specifying it on the command line. |
| -i file, --include file | Preloads an awk source file prior to running the main program. |
| -I, --trace | Enables tracing of the awk program. |
| -l library, --load library | Loads a dynamic extension library. |
| -L[value], --lint[=value] | Issues warnings for constructs that are either non-portable or questionable. |
| -M, --bignum | Activates gawks mpfr library for performing arbitrary-precision arithmetic. |
| -n, --non-decimal-data | Identifies octal and hexadecimal values within input data. |
| -N, --use-lc-numeric | Uses the locales numeric formatting. |
| -o file, --pretty-print[=file] | Redirects a pretty version of output to a file. |
| -O, --optimize | Enables optimization of the awk program. |
| -p[profile], --profile[=profile] | Enables profiling mode. |
| -P, --posix | Enables strict POSIX compliance. |
| -r, --reinterval | Enables interval expressions in regular expressions. |
| -s, --no-optimize | Disables optimization. |
| -S, --sandbox | Runs gawk in sandbox mode, restricting certain operations for security. |
| -t, --lint-old | Issues warnings for constructs that may not be compatible with older versions. |
| -V, --version | Displays version information and exits. |
Examples of gawk Command in Linux
The following are a few basic examples of gawk command in Linux systems −
- Print All Lines
- Print a Specific Column
- Print Lines Matching a Pattern
- Add Line Numbers
- Calculate the Sum of a Column
Print All Lines
By default, gawk command prints every line of data from a specified file, this can be done using the following example −
gawk '{print}' filename.txt
Print a Specific Column
The gawk command can be used to print a specific column of each line in a specified file. Lets say, to print the second column from a file named myfile.txt, use −
gawk '{print $2}' myfile.txt
Print Lines Matching a Pattern
You can also use gawk command to print lines from a file that contain a specific word. For example, to print a line that contains the word Users from a file called file.txt, run −
gawk '/Users/ {print}' file.txt
Add Line Numbers
Apart from printing the values using a specific pattern, you can also print each line with the line numbers. For example −
gawk '{print NR, $0}' filename.txt
In the above command, NR is a built-in variable that is used to represent the current record number (line number). $0 is a built-in variable that specifies the entire current record (line).
Calculate the Sum of a Column
With gawk command, it is also possible to calculate the sum of the values in a column. For example, to calculate the sum of the values in the first column in a file named file.txt, use −
gawk '{sum += $1} END {print sum}' filename.txt
In the above command, {sum += $1} instructs command to add the value in the first column ($1) to the variable sum for each line it processes. While the END {print sum} part ensures that after all lines have been processed, the total sum accumulated in the sum variable is printed.
Thats how you can use the gawk command on your Linux system.
Conclusion
The gawk command is a useful Linux utility that is widely adopted for text processing and data manipulation. By using the gawk command, you can search for patterns, perform actions on matching lines, utilize logical operators, string functions and arithmetic operations.
This tutorial has covered the installation of the gawk command on various Linux distributions, detailed its syntax, and explored the different options available. Additionally, it has also provided practical examples to help you understand how to effectively use the command on Linux systems.