On Linux, some web-servers (Apache in particular) close file with fd = 1 and
offer something else as stdout. Notable difference can be seen with a pipe and
an immediate redirection. Consider:
$ REQUEST_URI=/avatar/68b329da9893e34099c7d8ad5cb9c940 libravatarserv | cat > /tmp/response1.out
$ REQUEST_URI=/avatar/68b329da9893e34099c7d8ad5cb9c940 libravatarserv > /tmp/response2.out
$ diff -s /tmp/response{1,2}.out
Binary files /tmp/response1.out and /tmp/response2.out differ
Solution.
The output should be identical in both cases. So do not let ImageMagick to open
/dev/stdout by itself, instead write the resulted image to an in-memory buffer
and then to a file associated with the "cout" global object.
Nicholas Guriev
tastytea