Messages in this thread | | | Date | Mon, 26 Apr 1999 17:37:16 -0400 (EDT) | From | "Richard B. Johnson" <> | Subject | Re: sed not working on /proc files |
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On Mon, 26 Apr 1999, Stefan Monnier wrote:
> How do you explain the following problem (with 2.2.6): > > # (sed 's/a/a/') </proc/modules > # (cat | sed 's/a/a/') </proc/modules > nfsd 147288 1 (autoclean) > nfs 27856 2 (autoclean) > lockd 29000 1 (autoclean) [nfsd nfs] > sunrpc 48492 1 (autoclean) [nfsd nfs lockd] > autofs 8872 1 (autoclean) > 3c59x 17456 1 (autoclean) > opl3 10264 0 > cs4232 2264 0 > ad1848 15152 0 [cs4232] > uart401 5628 0 [cs4232] > sound 55080 0 [opl3 cs4232 ad1848 uart401] > soundcore 2208 6 [sound] > binfmt_misc 3108 0 > st 23352 0 > softdog 948 1 > unix 10056 72 (autoclean) > # >
-r--r--r-- 1 root root 0 Apr 26 17:28 /proc/meminfo ^_______ zero
It happens because files in /proc have zero length. These are not real files. To use `sed` and utilities that do lseek you can `cat` through a pipe as you have done. Sed's first 'lseek()' returns ESPIPE which tells it to not do that again -- and everything is fine.
Cheers, Dick Johnson ***** FILE SYSTEM WAS MODIFIED ***** Penguin : Linux version 2.2.6 on an i686 machine (400.59 BogoMips). Warning : It's hard to remain at the trailing edge of technology.
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