Fast, built-in pipe-based data sink
# with >/dev/null: $ time dd if=/dev/zero bs=1K count=100000 >/dev/null 100000+0 records in 100000+0 records out 102400000 bytes (102 MB) copied, 0.0355178 s, 2.9 GB/s real 0m0.037s user 0m0.011s sys 0m0.025s # with |: $ time dd if=/dev/zero bs=1K count=100000 |: real 0m0.002s user 0m0.000s sys 0m0.002s
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Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?
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help ::: : Null command. No effect; the command does nothing. Exit Status: Always succeeds.ls |: ; echo ${PIPESTATUS[@]}141 0 where >/dev/null makes no errortime sh test/spew.sh > /dev/nullreal 0m0.285s user 0m0.148s sys 0m0.136stime sh test/spew.sh |:real 0m0.008s user 0m0.000s sys 0m0.008scat spew3.shfor i in `seq 1 100` do for j in `seq 1 100` do echo i done done I think this is the usage the author intended, and it does seem to be much faster.cat|:now type in some letters. See how they get echoed to the screen. Now hit a newline. What happens? . now contrast this with:cat>/dev/nullwhich will soak up all kinds of control char except ^drany:~$ time >/dev/nullreal 0m0.000suser 0m0.000ssys 0m0.000srany:~$ time :|:real 0m0.002suser 0m0.008ssys 0m0.000srany:~$ls fools: foo: No such file or directoryperl -e 'print 0 for 1..10000; open FOO, ">foo"' |:ls fools: foo: No such file or directoryperl -e 'print 0 for 1..10000; open FOO, ">foo"' > /dev/nullls foofootime for x in {1..1000} ; do cat /tmp/VAR.log >/dev/null ; donereal 0m2.956suser 0m0.320ssys 0m0.790stime for x in {1..1000} ; do cat /tmp/VAR.log :| ; done-bash: syntax error near unexpected token `;'time for x in {1..1000} ; do cat /tmp/VAR.log |: ; donereal 0m4.903suser 0m0.380ssys 0m1.480sanyway, it seems to take longer for me. Shorter to type though.