Permission denied creating directory after switching user

Question

I switched to a different user with the su command, and now I want to create a file/folder but "permission denied" error appears.

safi_test4@safi-VirtualBox:/home/safi$ su safi_test4
Password:
safi_test4@safi-VirtualBox:/home/safi$ whoami
safi_test4
safi_test4@safi-VirtualBox:/home/safi$ mkdir try
mkdir: cannot create directory `try': Permission denied
safi_test4@safi-VirtualBox:/home/safi$

Answer 1

You switched to a new user but you are still under the user safi home directory. safi_test4 does not have permission to create files in the safi home directory.

Run the following command to switch to the safi_test4 home directory:

cd

Answer 2

You are running su safi_test4 but you should be running su safi.

Your prompt quite strongly suggests that you started out as the same user you became with su:

safi_test4@safi-VirtualBox:/home/safi$

Specifically:

• Although it can be set up otherwise, usually when a shell prompt starts with text followed by a @ character, the text it shows before that character is the name of the current user.
• When a prompt ends in a :, followed by some text, followed by a $, that text between the : and the $ usually represents the current directory. Furthermore, a directory named /home/safi is very likely the home directory of a user named safi.

This is to say that you appear to have used the cd command to enter the home directory of safi, but then you used a su command that did not change your identity to safi.

Assuming the usual permissions are set, safi_test4 will not be able to create files in the home directory of safi. Furthermore, it's unlikely you intended to use su to take on the identity that you already had.

To use su to take on the identity of another user, you should pass the name of the user you want to become as the argument to su, not the name of the user you currently are:

su safi

Though you might consider using this command instead, which will run a login shell as safi:

su - safi

When you do that, you get an environment like what you would get if you had logged in as safi by other means (like on a virtual console or via SSH). This has the additional minor benefit that you don't have to separately cd to safi's home directory.

Note that when you use su you must enter the target user's password. That is, for su safi to succeed you must enter safi's password, not safi_test4's password (unless they happen to be the same).

Answer 3

As mchid answer states you can use:

cd

to change to the home directory of the current user safi_test4. However on my system it doesn't work due to a function that gets in the way:

$ cd

cd: missing operand

Usage:

    cd ~            Change to home directory. Equivelent to 'cd /home/$USER'

    cd -            Change to previous directory before last 'cd' command

    cd ..           Move up one directory level

    cd ../..        Move up two directory levels

    cd ../sibling   Move up one directory level and change to sibling directory

    cd /path/to/    Change to specific directory '/path/to/' eg '/var/log'

    cd $OLDPWD      Change back to previous directory (similar to "cd -").

In this case on my system I must always type:

cd ~

Note that the regular cd command also supports the usages described above.

cd help screen

Here is how I get the cd help screen but be warned some people have criticized it. Edit your ~/.bashrc and put in these lines:

cd() {
    if [[ $# -eq 0 ]] ; then
        cat << 'EOF'

cd: missing operand

Usage:

    cd ~            Change to home directory. Equivelent to 'cd /home/$USER'

    cd -            Change to previous directory before last 'cd' command

    cd ..           Move up one directory level

    cd ../..        Move up two directory levels

    cd ../sibling   Move up one directory level and change to sibling directory

    cd /path/to/    Change to specific directory '/path/to/' eg '/var/log'

    cd $OLDPWD      Change back to previous directory (similar to "cd -").

EOF
        return
    fi

    builtin cd "$@"
} # cd ()