Anything related with user accounts and user management on Unix-like systems.

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5
votes
1answer
4k views

What is hvc0? (appearing in “who” list)

I have an Ubuntu Server, and when I type who, to see who's connected, I can see that there's a user connected, and instead of being logged to a pts/x, he's connected to hvc0. Is there something to ...
4
votes
2answers
4k views

How do I give all the permissions to a file for a single user that's not me?

When I want to grant access to another user to my file, I use chmod 777 file, but if I want to be sure I'm granting permission just for that user, how can I do it? -- update The file is owned by ...
7
votes
4answers
347 views

How can I safely give a shell to somebody?

I have a question about giving a shell account to somebody. How safe is it? He could read /etc. How can I give a secured shell account that will only restrict the user to some bins and his own home? ...
3
votes
3answers
4k views

Why is file ownership inconsistent between two systems mounting the same NFS share?

I have one IBM AIX server (serverA) which is connected to the san storage. I have created a volume group and also file system (jfs2) and mounted to directory /profit. After that I created a NFS ...
4
votes
3answers
3k views

How to find the machine from which a user logged into current machine using ssh?

In a multi server architecture, is it possible to find out from which machine a user logged into current machine using ssh? For example, user1 logged into host1. From there, the user logged into ...
3
votes
3answers
2k views

Reset all groups to default

I recently set up some groups and users on my machine, and now I want to remove all those users and all those groups. Somewhat stupidly, I read on an Ubuntu forum or something like that that it was ...
6
votes
1answer
2k views

Why can't I use arrow keys in terminal on Debian 6? (nonroot)

When I am on a non-root user I cannot use ↑/↓ to list my previous commands, and if I am typing I can't use ←/→ to say, add in a directory or to correct the ...
2
votes
1answer
3k views

How do I add a new user to an embedded Linux system by hand?

I have a system which was designed for use by root only and I want to run an FTP server on it. The software I use handles authentication by using same username and password as OS itself. To me it ...
3
votes
2answers
984 views

How to trace a process to original user?

Say, on a Solaris server, user1 logs in, switches to someother user, say sruser, using su - and then starts a process of id X. And then another user user2 logs in, switches to sruser the same way and ...
4
votes
1answer
498 views

How to disable certain system calls for a given user?

I am creating a web app similar to codepad and for each run-action my app copies a directory (/home/radeks/voidptr/private/chroot-root) to /tmp/voidptr/[random-id]/chroot-root. This chroot directory ...
2
votes
2answers
2k views

How to get hashed password in /etc/shadow using getpwnam()?

Apparently there is a function (getpwnam) that given a username, will return the appropriate entry in /etc/passwd with the other details for that user (shell, uid, gid, etc.). However, I have no idea ...
5
votes
2answers
5k views

Add all users in one group to another group?

I have some users in a group called aa and I need to give them the rights to write to a folder which is currently tomcat:tomcatdeploy. The straightforward way to do this is to add all the users to ...
5
votes
1answer
726 views

Why root's default shell is configured differently with other normal user account's default shell?

As I know, root's default shell is configured csh and normal user's default shell is sh in FreeBSD. And in Ubuntu, root is dash, normal user is bash. (refer: What's the Ubuntu's default shell?) Why ...
8
votes
4answers
1k views

Multiple Users on a Desktop Environment

This is probably a REALLY stupid question. But anyways, lets pretend we had a *nix rather powerful system... Now Obviously I know you can set up multiple users to login to a system.......but how ...
2
votes
3answers
457 views

su and aliases confusion

I create an alias as my current user in the bash shell, which I can see using the alias command. When I switch user without the -, i.e. su testuser, the alias is not carried into the new user's ...
14
votes
4answers
11k views

How do I completely disable an account?

How do I completely disable an account? passwd -l will not allow anyone to log into an account using a password but you can still log in via private/public keys. How would I disable the account ...
1
vote
3answers
198 views

How to make files created by a specific user to have specific permissions by default

Here's a sequence of commands and the resulting output: $ touch testfile $ stat -c'%a %A' testfile 644 -rw-r--r-- What must I do so that when a user follows that sequence, I get this output ...
2
votes
4answers
3k views

NIS: How to allow access to both local and remote users' home directories?

We have a NIS server with shared users' home directories in '/home'. We're used to mounting the server's '/home' using '/home' as the mount point on each NIS client. However, if we do this with a ...
10
votes
3answers
3k views

How can I make a user able to log in with ssh keys but not with a password?

I would like to create a user and have no password. As in you cant log in with a password. I want to add keys to its authorized_keys by using root. This is for my automated backup system.
3
votes
1answer
659 views

Set visible directories for SFTP access?

I am setting up SFTP access to one of my machines running Linux with the Dropbear SSH server. When I SFTP onto the machine remotely, I can see the entire filesystem on it, even if I might not have ...
2
votes
1answer
116 views

rc control user

I am playing around with rc scripts. I am starting a daemon from rc.local. I would like to know how I start the process under a specific user instead of root?
4
votes
4answers
230 views

How do I check what 'normal' users are there on the system?

I want to find out what 'normal' users are available on a system. By normal, I mean those who are manually created, not those like sshd or gdm.
6
votes
3answers
4k views

Why are underscores not allowed in usernames in some distros (Debian for example)

So why has the underscore been considered a bad character for user names in Debian (and possibly other distributions) while it has been removed from adduser's NAME_REGEX in Ubuntu?
6
votes
2answers
5k views

I added a user to a group, but group permissions on files still have no effect

I changed permissions of a file (chmod g+w testfile) and running ls -l testfile gives: -rwxrwxr-x 1 user1 user1 0 2011-01-24 20:36 testfile I then added a user to that group ("/etc/group" has ...
3
votes
2answers
883 views

PHP interface to manage linux user accounts

I have a linux web & samba server. I need to give administrators access to manage minor accounts & groups. Is there a secure php web interface that can do this? I don't want to give them shell ...
5
votes
3answers
461 views

Unix users, groups, and permissions

I don't understand unix users, groups, permissions, etc. For example, things managed by the chmod, chgrp, usermod, groupadd, etc. commands. How do all these things work?
12
votes
1answer
2k views

Can one PC be used by two users at the same time via dual-monitor?

Since modern PCs can use two screens at the same time I wonder if it is possible to plug in two keyboards and mouses as well to have the two screens run two (more or less) independent X-sessions at ...
12
votes
3answers
4k views

Creating a user who cannot get an interactive shell

What are interactive and non-interactive shell? Questions: Create a user john who should not get an interactive shell. How can we do this?
1
vote
2answers
124 views

How would you create a user with the HOME_DIR field in /etc/passwd completely blank?

Closest I can come is: useradd --home / -r --shell /sbin/nologin someuser But this creates an entry into /etc/htpasswd that looks something like this: someuser:x:100:100::/:/sbin/nologin I want ...
3
votes
2answers
743 views

In new users's home directory create sub-directory with a specific group and permissions

Linux will copy the the contents of /etc/skel when a new user is created. I want to have a sub-directory in each user's home directory, MyStevedore. I want this directory to have the owner be the new ...
57
votes
3answers
198k views

How to switch between users on one terminal?

I'd like to log in as a different user without logging out of the current one (on the same terminal). How do I do that?
2
votes
2answers
398 views

Unix executable file permission vs runtime user's permissions

I have heard that it is good practice to run an executable as a user with a completely different privilege set than the owner of the task. In fact I heard that it is best to run it as a different user ...
6
votes
7answers
2k views

Is it bad practice to set root's shell to something other than the default?

Once a friend of mine (who is an experienced Unix/Linux user) told me that setting root's shell to something other than sh (i.e bash or zsh) might create problems, because some script might assume ...
52
votes
4answers
11k views

What are other ways to share a tmux session between two users?

I'm looking for a clean and easy way to share a tmux session with another user on the same machine. I've tried the -S socket-path option, but it requires opening up all permissions of the socket-path ...
9
votes
2answers
23k views

User's Login date and login time

I want to fetch user's login time and login date, is there any command in Unix providing User's login date and User's login time ? this problem i want to perform in Shell-script where username is ...
10
votes
1answer
6k views

Meaning of root:wheel

What does root:wheel mean in the following? chown root:wheel myfile
12
votes
11answers
1k views

Concern about logging in as root overrated?

For personal linux on my personal notebooks, I've usually set my environment to autologin as root even under X or lower runlevels. I've found my workflow is very pleasant and fast, without any ...
4
votes
5answers
376 views

Setting up a family server

I'm very new to Unix, but after having become comfortable with bash over the past year and after having played with Ubuntu recently, I've decided to make my next computer run Ubuntu, and I think my ...
12
votes
3answers
1k views

Can I limit a user (and their apps) to one network interface?

As the title really. I've actually got two scenarios to apply this: Multiseat Desktop: two network connections both with internet gateways and two accounts doing bandwidth-intensive tasks on each. I ...
6
votes
9answers
459 views

What is/are the standard CLI program(s) to manage users and groups?

As the title says, I'm basically asking about user management from the command line (e.g. on a system where there are no graphical tools available). In the past I've used several different programs to ...
27
votes
4answers
9k views

Is it possible to rename a Unix user account?

I installed Ubuntu on a computer that is now used by somebody else. I renamed the account with her name, but it only changes the fullname, not the user name, which is still displayed in the top right ...
29
votes
7answers
18k views

How do you kick a benign user off your system?

I was googling this a bit ago and noticed a couple of ways, but I'm guessing that google doesn't know all. So how do you kick users off your Linux box? also how do you go about seeing they are logged ...
13
votes
2answers
5k views

How can I determine if someone's SSH key contains an empty passphrase?

Some of my Linux & FreeBSD systems have dozens of users. Staff will use these "ssh gateway" nodes to SSH into other internal servers. We're concerned that some of these people use an unencrypted ...
18
votes
10answers
3k views

How to create strong passwords in Linux?

I wonder how I can create strong passwords on Linux (for both normal and admin users) and if there are specific programs to do that.
20
votes
6answers
11k views

How do you create a user with no password?

In os X it's possible to have users without passwords. If you inspect them with dscl their password show up as *. This is used for system users such as users for databases like mysql, pgsql etc. ...