WRJPGCOM(1)

🌸 NAME 🌸

okay bestie, meet wrjpgcom — this is the wrjpgcom(1) manual page, and it's literally here to insert text comments into a JPEG file. no cap. 💅

✨ SYNOPSIS ✨

wrjpgcom [ -replace ] [ -comment text ] [ -cfile name ] [ filename ]

🎀 DESCRIPTION 🎀

So here's the vibe: wrjpgcom reads the named JPEG/JFIF file — or standard input if no file is named — and generates a new JPEG/JFIF file on standard output. A comment block is added to the file. iconic behavior. 🦋

The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file. Although the standard doesn't actually define what COM blocks are for, they are widely used to hold user-supplied text strings. This lets you add annotations, titles, index terms, etc to your JPEG files, and later retrieve them as text. COM blocks do not interfere with the image stored in the JPEG file. The maximum size of a COM block is 64K, but you can have as many of them as you like in one JPEG file. 💖

wrjpgcom adds a COM block, containing text you provide, to a JPEG file. Ordinarily, the COM block is added after any existing COM blocks; but you can delete the old COM blocks if you wish. lowkey powerful.

🌈 OPTIONS 🌈

Switch names may be abbreviated, and are not case sensitive.

• -replace — Delete any existing COM blocks from the file.
• -comment text — Supply text for new COM block on command line.
• -cfile name — Read text for new COM block from named file.

If you have only one line of comment text to add, you can provide it on the command line with -comment. The comment text must be surrounded with quotes so that it is treated as a single argument. Longer comments can be read from a text file. 🫶

If you give neither -comment nor -cfile, then wrjpgcom will read the comment text from standard input. (In this case an input image file name MUST be supplied, so that the source JPEG file comes from somewhere else.) You can enter multiple lines, up to 64KB worth. Type an end-of-file indicator (usually control-D) to terminate the comment text entry. 🧚

wrjpgcom will not add a COM block if the provided comment string is empty. Therefore -replace -comment "" can be used to delete all COM blocks from a file. 💀 not me deleting every comment block with one empty string, but okay!

🍓 EXAMPLES 🍓

Add a short comment to in.jpg, producing out.jpg:

wrjpgcom -c "View of my back yard" in.jpg > out.jpg

Attach a long comment previously stored in comment.txt:

wrjpgcom in.jpg < comment.txt > out.jpg

or equivalently

wrjpgcom -cfile comment.txt < in.jpg > out.jpg

👑 SEE ALSO 👑

cjpeg(1), djpeg(1), jpegtran(1), rdjpgcom(1)

💜 AUTHOR 💜

Independent JPEG Group

mwah 💋 that's the whole page, bestie — wrjpgcom(1), dated 15 June 1995, brought to you by the Independent JPEG Group. periodt. 🎀