impaste: pasting images to piped commands on macOS#

I wanted the ability to paste the image on my clipboard into a command in the macOS terminal.

It turns out pbpaste only works with textual data - so copying a portion of a screenshot to my clipboard (using CleanShot X) and running the following produced a 0 byte file:

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pbpaste > /tmp/screenshot.png

With some initial clues from Feraidoon Mehri in a GitHub issue followed by some ChatGPT and Claude 3 Opus prompting I got to the following script, saved as ~/.local/bin/impaste on my machine (that folder is on my PATH) and made excutable with chmod 755 ~/.local/bin/impaste:

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#!/bin/zsh
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# Generate a unique temporary filename
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tempfile=$(mktemp -t clipboard.XXXXXXXXXX.png)
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# Save the clipboard image to the temporary file
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osascript -e 'set theImage to the clipboard as «class PNGf»' \
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  -e "set theFile to open for access POSIX file \"$tempfile\" with write permission" \
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  -e 'write theImage to theFile' \
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  -e 'close access theFile'
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# Output the image data to stdout
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cat "$tempfile"
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# Delete the temporary file
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rm "$tempfile"

Now I can copy an image to my clipboard and run this:

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impaste > /tmp/image.png

Or pipe impaste into any command that accepts images.