From: Bob Proulx <b...@proulx.com> Date: Wed, 27 Mar 2013 11:20:35 -0600
> Masato Asou wrote: >> 1. Go to directory ~/src. >> $ cd ~/src >> 2. Rename the directory to ~/src-old. >> $ mv ~/src ~/src-old >> 3. Invoke pwd command. Then print /home/asou/src by pwd command. >> $ pwd >> /home/asou/src >> 4. Invoke /bin/pwd command. Then print /home/asou/src-old. >> $ /bin/pwd >> /home/asou/src-old >> >> Is this a bug of internal pwd command? > > This is an intentional feature. Bash tracks your present working > directory as changed by the cd command in the PWD variable. The pwd > command prints that variable. When you arrived at the location > $HOME/src the location was stored in the PWD variable. Moving it out > from under your current process had no effect on the value of the PWD > variable. Calling pwd prints the content of PWD variable. Thank you for your careful comment. > In the pwd documentation this is described briefly along with the -L > and -P options for "logical" and "physical" behavior. By default bash > follows the logical chain of directories when performing commands > which change the current directory. The logical status is how you got > there. The intention is to make symbolic links invisible to the user. > You could cd to a symlinked directory and then 'cd ..' would back you > one logical directory out and return you to where you were. Using a > physical view the directory change through a symlink would place you > in the new directory and a 'cd ..' would take you up from there. > If you 'set -o physical' then bash will use the canonical physical > structure of the file system when performing commands which change > directories. Sorry, I forgot to confirm the man bash. > Personally I dislike the problems associated with the shell's logical > view and always have 'set -o physical' in my .bashrc file so that I > see the canonical physical file system directory structure. I also agree with your opinion. > The > logical view is a thin facade that is too easily broken. But the > majority of users seem to prefer the logical view just the same. Thanks. -- ASOU Masato
