EXIT STATUS
The exit status of is

0   Success

20  #ifdef XCF2FOO Problems parsing the command line, including unknown color names (or missing color name directory) for -b. #else Problems parsing the command line. #endif

21  The specified XCF file does not exist or cannot be read. #ifdef XCF2FOO

22  A layer named on the command line was not found, or the --mask option was used for a layer that has no layer mask. #ifdef XCF2PNM

100 Transparent pixels were found, but neither -a nor -b was given.

101 The -a option was given yet the image has no transparency. (Use -A to go on anyway). #endif

102 The -G option was given, yet partial transparency was found.

103 #ifdef XCF2PNM -g (or -m) was given, yet colored (or gray) pixels were found. #else -g was given, yet colored pixels were found. #endif #endif

123 The XCF file contains presumably valid features that xcftools does not support. (As of this writing there is no known way of getting the Gimp to write an XCF file that will provoke this return. Please notify the author if you discover one).

125 The XCF file is malformed.

126 An uncompression program could not be executed, or terminated abnormally.

127 Unexpected I/O error, internal errors, or other "this can't happen" situations.

If an uncompression program returns an error exit status, this will be returned from too.