Useful use of cat? (was Re: This Week's Useless Use of Cat Award goes ?to...)
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From: pk on 25 Feb 2010 19:12 Alan Curry wrote: > In article <hm65o5$qq3$1(a)speranza.aioe.org>, pk <pk(a)pk.invalid> wrote: > |Apparently "gzip" is (or was) such a software on some systems. > > Look at the timestamps on the releases (from ftp.gnu.org): > > -rw-r--r-- 1 1003 65534 220623 Aug 20 1993 gzip-1.2.4.tar.gz > -rw-r--r-- 1 1003 65534 220774 Feb 03 1999 gzip-1.2.4a.tar.gz > > Between 1993 and 1999 there was no gzip release. At the beginning of that > time frame, files larger than 2G were not really common, and OS support > for them was still under development. It would have been almost impossible > for gzip to support large files at the time 1.2.4 was released. > > But by the time the next release came, large file support at the libc > level was basically universal, and gzip was one of the last stragglers > that didn't make use of it (unless the OS vendor included a patched gzip, > or the OS was full-on 64-bit-only in which case it was never an issue) > > Actually, on taking a closer look, 1.2.4a didn't even include any code > changes, so it didn't support large files either. gzip didn't catch up > until 1.3, released in late 2001! Thank you! Now I understand the context in which that use of cat makes sense.
From: Sven Mascheck on 25 Feb 2010 19:15 Alan Curry wrote: > It would have been almost impossible for gzip to support large files at > the time 1.2.4 was released. I was too quick with "bug". > Actually, on taking a closer look, 1.2.4a didn't even include any code > changes, so it didn't support large files either. I haven't tried to find out where the toolkit might fail, but ironically recompiling 1.2.4 with just having added "-D_FILE_OFFSET_BITS=64" to the CFLAGS allows gzip to compress a 2G file. At least with a current libc, __lxstat64(3, "./large", 0x806f520 <unfinished ...> SYS_lstat64(0x808f9c0, 0x806f520, 0xb7f95ff4, 0x808f9c0, 0x80a460c) = 0 <... __lxstat64 resumed> ) = 0
From: pk on 25 Feb 2010 19:14
Sven Mascheck wrote: > Alan Curry wrote: > >> It would have been almost impossible for gzip to support large files at >> the time 1.2.4 was released. > > I was too quick with "bug". > >> Actually, on taking a closer look, 1.2.4a didn't even include any code >> changes, so it didn't support large files either. > > I haven't tried to find out where the toolkit might fail, but ironically > recompiling 1.2.4 with just having added "-D_FILE_OFFSET_BITS=64" to the > CFLAGS allows gzip to compress a 2G file. At least with a current libc, Yes, I think that is expected, since defining that macro silently replaces all the "normal" calls with the 64-bit versions, so a recompilation should be all that's needed. I found this page helpful to understand the whole large file support thing: http://www.suse.de/~aj/linux_lfs.html |