On Wed, 2009-01-14 at 01:50 +0800, mobile Parmenides wrote: > Hi > > I am reading stable lfs book of 6.3 version. On page 96, I'm > puzzled to the following two commands: > > ln -sv ../usr/bin/cpp /lib > ln -sv gcc /usr/bin/cc > > For the first command, the current dircetory is /source/gcc-build, and > the path in the command does not exsit. For the second command, the > intendance is to make /usr/bin/cc point to gcc. But , gcc is in the > current directory, and after installing, the current directory is to > be deleted. What's the meaning of the link?
A little late replying, but where others have said read the man page, I don't personally find it very clear on the subject. The short version is that if you create a symlink with a relative path, that path is interpreted relative to the symlink itself, not to the current directory - hence, the first example should be read as /lib/../usr/bin/cpp, and the second as /usr/bin/gcc The reason is that the value you provide isn't interpreted when the symlink is created - it's interpreted when the symlink is actually referenced. If you try running ls on the links: ~$ ll /lib/cpp /usr/bin/cc lrwxrwxrwx 1 root root 14 2008-06-04 21:05 /lib/cpp -> ../usr/bin/cpp lrwxrwxrwx 1 root root 3 2008-06-04 21:05 /usr/bin/cc -> gcc See the file sizes - 14 bytes, and 3 bytes. The same number of characters in the '../usr/bin/cpp' and 'gcc' respectively. Not a coincidence. :) Note that as a result, a link pointing from /lib to ../usr/bin/cpp isn't the same thing as a link pointing to /usr/bin/cpp. The latter will always point to the same place, but the former will change if the location of the symlink does - e.g if /lib is mounted as /mnt/lfs/lib at some point. Hope that provides a little illumination... Simon.
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