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Accepted
Eric
Asked: 2012-05-26 17:23:17 +0800 CST

Why is touch failing?

  • 772

I must be missing something obvious.

This works:

[root@host2 /]# cd /home/mysite/public_html/../logs 
[root@host2 /home/mysite/logs]# touch x

Why doesn't this?

[root@host2 /]# touch /home/mysite/public_html/../logs/x
touch: cannot touch `/home/mysite/public_html/../logs/x': No such file or directory
linux ubuntu

2 Answers

  1. Best Answer

    There's a good chance that one of the directories in /home/mysite/public_html/../logs/ is actually a symbolic link. The cd command built into most modern shells does a little magic in this case, so that cd .. takes you to the "logical" parent directory -- which takes into account how you got there.

    When you try to touch /home/mysite/public_html/../logs/x, you don't get this magic.

    Consider:

    $ ls -l /home/lars
public_html -> /var/www/lars
logs/

    If I cd /home/lars/public_html I'm actually inside of /var/www/lars. So technically, ../logs does not exist (because the logs directory I want is actually in /home/lars, not in /var/www, which is the "real" parent of /var/www/lars.

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  2. public_html is a symlink to somewhere completely different. As a shell, bash tracks symlinks in paths differently than many other programs do. Try this: cd /home/mysite/public_html then run pwd (the bash command) and /bin/pwd (the program). When touch tries to use the path, it will go to /var/www/sites/mysite/ or wherever that link points, then go up a directory from there to get to logs/... only to fail to find /var/www/sites/logs/.

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