On Wed, 25 Jul 2007 07:30:37 +0200, Rene Herman said: > Yes, but what's locate's usage scenario? I've never, ever wanted to use it. > When do you know the name of something but not where it's located, other > than situations which "which" wouldn't cover and after just having > installed/unpacked something meaning locate doesn't know about it yet either?
My favorite use - with 5 Fedora kernels and as many -mm kernels on my laptop, doing a 'locate moby' finds all the moby.c and moby.o and moby.ko for the various releases. For bonus points, something like: ls -lt `locate iwl3945.ko` to find all 19 copies that are on my system, and remind me which ones were compiled when. Or just when you remember the name of some one-off 100-line Perl program that you wrote 6 months ago, but not sure which directory you left it in... ;) You want hard numbers? Here you go - 'locate' versus 'find' (/usr/src/ has about 290K files on it): % strace locate iwl3945.ko >| /tmp/foo3 2>&1 % wc /tmp/foo3 96 592 6252 /tmp/foo3 % strace find /usr/src /lib -name iwl3945.ko >| /tmp/foo4 2>&1 % wc /tmp/foo4 328380 1550032 15708205 /tmp/foo4 # echo 1 > /proc/sys/vm/drop_caches (to empty the caches % time locate iwl3945.ko > /dev/null real 0m0.872s user 0m0.867s sys 0m0.008s % time find /usr/src /lib -name iwl3945.ko > /dev/null find: /usr/src/lost+found: Permission denied real 1m12.241s user 0m1.128s sys 0m3.566s So 96 system calls in 1 second, against 328K calls in a minute. There's your use case, right there. Now if we can just find a way for that find/updatedb to not be as painful to the rest of the system.....
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