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Is it possible to redefine the home directory? e.g. to /ext1/username instead of /home/username, i.e. expanding the ~ to another directory (as opposed to changing the actual home directory where users' home files are located).
(This question is mostly academic, as it seems like bad practice to do so. I also have no choice in the matter of using csh, despite having read the Top 10.)
The tilde ~ is interpreted by your shell. Your shell will interpret ~ as a short form of $HOME.
Try (echo ~; HOME=foo; echo ~). This should first print your real home directory and afterwards "foo", as you set $HOME to that.
The default value of $HOME comes from you system configuration. Use getent passwd to list all known users and their home directories. Depending on your system configuration those entries might come from /etc/passwd or any remote directory service.
If you only want to temporarily redefine your home directory, just set another $HOME.
If you permanently want to change it you have to change the passwd entry, e.g. by manually editing /etc/passwd.
csh the relevant variable is $home (lowercase), and you can't setenv HOME /ext1/acheong—you can only set home=/ext1/acheong, and that worked for me.)
Dec 4, 2013 at 14:50
vipw (or whatever GUI your OS provides) rather than editing /etc/passwd directly. Direct editing risks corrupting the file, which can be difficult to recover from.
Dec 4, 2013 at 20:45
The value that is used for ~ is determined from the value you get from the administrative database (getent passwd), typically in the /etc/passwd file, for each user's home directory that's defined there.
$ cat /etc/passwd
root:x:0:0:root:/root:/bin/bash
sam:x:500:500:Sam Mingolelli:/home/sam:/bin/bash
tracy:x:501:501::/home/tracy:/bin/bash
The 6th column in this file is where the value used when someone types cd ~ comes from.
You can see what a system would use for the user's home directory using the command getent passwd:
$ getent passwd
root:x:0:0:root:/root:/bin/bash
sam:x:500:500:Sam Mingolelli:/home/sam:/bin/bash
tracy:x:501:501::/home/tracy:/bin/bash
The "database" that provides these is controlled through your systems resolver, defined in /etc/nsswitch.conf.
$ grep passwd /etc/nsswitch.conf
#passwd: db files nisplus nis
passwd: files
Files above means /etc/passwd, but the "database" could come from LDAP, NIS, or other locations over the network, for example.
To perform this operation is a little tricky after the accounts have been created. If you're creating accounts from scratch then it's trivial to redefine a user's location of their home directory. When running the useradd command you can specify the location to be used for a user's home directory.
$ useradd -d /ext1/acheong ...
excerpt from man page
-d, --home HOME_DIR
The new user will be created using HOME_DIR as the value for the user’s
login directory. The default is to append the LOGIN name to BASE_DIR and
use that as the login directory name. The directory HOME_DIR does not
have to exist but will not be created if it is missing.
This becomes more of a surgical operation since often times the path of a user's home directory gets included statically in configuration files, making it trickier.
$ grep home /home/sam/.*
/home/sam/.gtkrc-1.2-gnome2:include "/home/sam/.gtkrc.mine"
These will either need to be fixed, or you'll have to provide a link from /home/sam to the new location, /ext1/sam.
/etc/passwdIf the system is getting the home directories from LDAP, NIS, etc. then you'll need to peform the relocation in those systems, and coordinate with moving the files from /home/sam to /ext1/sam.
If the reason is to spread out users across multiple file systems, you could also use the automounter. And even allow you to have a different "base" directory for your users.
~to something other than the actual home directory?~to another directory (not, if I understand your alternative correctly, changing where all users' home directories are to be located). I didn't realize that~was interpreted as a short form of$HOME, as @michas described in his answer.