hmcm@helen:~$ perl -e 'use POSIX; mkfifo("four", 0444);'
hmcm@helen:~$ ls -l four
pr--r--r-- 1 hmcm hmcm 0 2007-10-25 13:33 four

hmcm@helen:~$ perl -e 'use POSIX; mkfifo("five", 0555);'
hmcm@helen:~$ ls -l five
pr-xr-xr-x 1 hmcm hmcm 0 2007-10-25 13:34 five

hmcm@helen:~$ perl -e 'use POSIX; mkfifo("six", 0666);'
hmcm@helen:~$ ls -l six
prw-r--r-- 1 hmcm hmcm 0 2007-10-25 13:35 six

hmcm@helen:~$ perl -e 'use POSIX; mkfifo("seven", 0777);'
hmcm@helen:~$ ls -l seven
prwxr-xr-x 1 hmcm hmcm 0 2007-10-25 13:36 seven