Re: undeterministic output when running egrep repeatedly with the same input

[Robert Millan <rmh@debian.org>]

On 20/01/2014 23:12, Robert Millan wrote:
> $ for i in $(seq 100) ; do egrep '^#[[:space:]]*define[[:space:]]+MNT_[A-Z]+[[:space:]]+0x[0-9]+[[:space:]]*' /usr/src/kfreebsd-headers-10.0-1/sys/sys/mount.h | grep MNT_RDONLY | head -n 1 ; done | wc -l
> 72

Interestingly, when the receiving end of the pipe egrep writes to is not spawned
in each iteration, the chance of failure is much lower (but still non-zero):

$ for i in $(seq 100) ; do for i in $(seq 100) ; do egrep '^#[[:space:]]*define[[:space:]]+MNT_[A-Z]+[[:space:]]+0x[0-9]+[[:space:]]*' /usr/src/kfreebsd-headers-10.0-1/sys/sys/mount.h ; done | grep MNT_RDONLY | wc -l ; done
100
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100

-- 
Robert Millan