How to use the command pgmtopgm (with examples)

The pgmtopgm command is a part of the Netpbm package and is used to convert PGM (Portable Graymap) image files. It can be used for various tasks such as copying PGM files, displaying the version information, etc.

Use case 1: Copy a PGM file from stdin to stderr

Code:

pgmtopgm

Motivation: This use case is useful when you want to copy a PGM image file from standard input (stdin) to standard error (stderr). It can be handy in scenarios where you need to quickly check the contents of a PGM file or need to perform some debugging on the file.

Explanation: The pgmtopgm command without any arguments and file names reads the PGM image file from standard input (stdin) and writes the binary representation of the file to standard error (stderr).

Example output: Suppose you have a PGM image file called “image.pgm” with the following content:

P2
# This is a comment
4 3
255
0 0 0 0 0 0 0 0 0 0 0 0
255 255 255 255 255 255 255 255 255 255 255 255

To copy the contents of “image.pgm” to standard error, you can use the following command:

cat image.pgm | pgmtopgm

The above command will output the binary representation of the PGM file on the terminal without modifying the actual image file.

Use case 2: Display version

Code:

pgmtopgm -version

Motivation: This use case is useful when you want to check the version of the pgmtopgm command. It can be helpful to ensure that you have the desired version and to troubleshoot any issues related to compatibility.

Explanation: The -version flag is used to display the version information of the pgmtopgm command.

Example output: Running the command pgmtopgm -version will display the version information of the pgmtopgm command. The output may look like this:

pgmtopgm version: 1.2

Conclusion:

The pgmtopgm command is a versatile tool for working with PGM image files. It allows you to copy PGM files, display the version information, and perform various other operations. By understanding the different use cases of the command and how to use them, you can efficiently work with PGM images.