The shasum utility has a a -p/--portable option with the following description:
-p, --portable read files in portable mode
produces same digest on Windows/Unix/Mac
I've never seen the inclusion this option change the digest of a file, and I'm not really sure what effect it's supposed to have either. What is this "portable mode" of reading files?
For what it's worth shasum says:
-p, --portable read in portable mode (to be deprecated)
As far as I can tell (I am no perl expert) it appears to be there to take into account different EOL characters.
The source code says:
The sums are computed as described in FIPS PUB 180-2. When checking, the
input should be a former output of this program. The default mode is to
print a line with checksum, a character indicating type (`*' for binary,
`?' for portable, ` ' for text), and name for each FILE.
...
# Try to figure out if the OS is DOS-like. If it is,
# default to binary mode when reading files, unless
# explicitly overriden by command line "--text" or
# "--portable" options.
...
I'm happy for any perl experts to look at the complete source code and confirm my answer.
