Resize images in a directory so they fit within a maximum width and height. Aspect ratio is always preserved. Files already within the limits are left untouched.

go install github.com/lxkrmr/shrink@latest

Requires Go. The binary lands in ~/go/bin/shrink, which should already be in your $PATH if you have used go install before.

shrink --max-width N --max-height N <dir>

At least one of --max-width or --max-height is required. Flags must come before the directory.

# resize everything in ~/Screenshots to fit within 1280×1280
shrink --max-width 1280 --max-height 1280 ~/Screenshots

# current directory, only constrain width
shrink --max-width 1920 .

Shell alias example:

alias shrink='shrink --max-width 1280 --max-height 1280 ~/Screenshots'

screenshot-big.png: 3200×2400 → 1280×960 (4.2 MB → 0.9 MB)
screenshot-ok.png: ok (1024×768)

2 resized, 1 ok, 0 failed

Errors go to stderr. Exit code is 0 if all files were processed, 1 if any file failed.

PNG, JPEG. Files with other extensions are silently skipped.