Permissions are the unix way of controlling access to resources such as files, directories and devices and may be specified for an owner, group, or all users.

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How to (safely) move /tmp to a different volume?

Today the /tmp directory filled up on a machine at work. The problem was, it was on the root partition which wasn't very big. In order to fix this, a co-worker created a /new/tmp directory elsewhere, ...
5
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1answer
704 views

Give a specific user permissions to a device without giving access to other users

I have a card reader attached on /dev/sdb. What I do is giving all permissions to owner, group and the rest of the world, using: sudo chmod 777 /dev/sdb Can I just use another combination, ...
27
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6answers
14k views

Can a script be executable but not readable?

Is it possible to execute a script if there is no permission to read it? In root mode, I made a script and I want the other user to execute this script but not read it. I did chmod to forbid read and ...
12
votes
1answer
974 views

Can I restrict a user to use special programs?

Is it possible to add a user and restrict him to run special programs? For example after this user logs in, he can only open Firefox to use Internet and no other programs can be run by this user. For ...
11
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3answers
7k views

Can files be created with permissions set on the command line?

When creating directories, mkdir -m <mode> <dir> provides for creating one or more directories with the given mode/permissions set (atomically). Is there an equivalent for creating files, ...
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8answers
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Problem to launch java at Debian: “error while loading shared libraries: libjli.so”

I'm trying to launch java: $ java -version java: error while loading shared libraries: libjli.so: cannot open shared object file: No such file or directory $ ldd ...
9
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3answers
6k views

External hard drive permissions - ext4

I have an external USB 3 disk drive (2TB capacity) that is most likely going to be moved from machine to machine. The disk has a GUID partition table and an ext4 partition. I am unable to write to the ...
8
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5answers
15k views

How to get back sudo on Ubuntu?

I have done this: sudo chown -R myname /usr/ and now I can't use the sudo command because of this error: sudo: must be setuid root And as I read this means that the owner of this file ...
12
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2answers
10k views

Uppercase S in permissions of a folder

What does the letter S mean below? The file in question is a folder.                                     ...
10
votes
1answer
11k views

Group within group file permissions

I tried finding this on here, but couldn't so sorry if it's a duplicate. Say I have 2 groups and a user: group1, group2, user1 with the following structure: group1 is a member of group 2, user1 is a ...
6
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2answers
213 views

Folder with ONLY write permission is useless… right?

Having worked with Linux for years, and finding myself with some free time, I decided to revisit some basics. So I re-read the stuff about permissions (without checking source code), and its special ...
6
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3answers
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granting write permissions to a group to a folder

How can I grant write permission to 1 group ? I have 2 users (alex and ben). alex is member of group alex and of group consult. ben is member of group ben and of group consult. I want to grant read ...
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2answers
16k views

Mount device with r/w access to specific user

How can I mount some device with read-write access to specific user?
2
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2answers
696 views

Is a -rw-rw-rw- file really inaccessible inside a drwxrwx— directory?

Say I have a directory with these permissions: drwxrwx--- Inside this directory, a file with these permissions: -rw-rw-rw- Is the file readable/writable by everyone or not ? If not, how secure ...
2
votes
1answer
1k views

How do I restore default owner of files in /var/ directory? [duplicate]

Accidentally in /var/ directory I ran chown root . -R;chgrp root . -R. Now services like mysql don't start. Is there a way to restore default owner and groups? If there is no way, what is the default ...
9
votes
1answer
7k views

Why does root get Permission denied when accessing FUSE directory?

I use a FUSE filesystem with no problems as my own user, but root can't access my FUSE mounts. Instead, any command gives Permission denied. How can I give root the permission to read these mounts? ...
8
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2answers
3k views

Evince fails to start because it cannot read .Xauthority

I'm logged in remotely over SSH with X forwarding to a machine running Ubuntu 10.04 (lucid). Most X11 applications (e.g. xterm, gnome-terminal) work fine. But Evince does not start. It seems unable to ...
7
votes
1answer
4k views

Symbolic link permissions

I have access to a remote Linux machine where everytime I create a symbolic link, it is created by default with the following permissions: lrwxrwxrwx If I try to change the permissions of the ...
7
votes
1answer
7k views

I can't remove a directory tree with rm -rf

This seems very strange to me. I'm running kernel 2.6.37.2 and ran: ~]$ cp -r /proc/ here ~]$ rm -rf here I get some permission denies when copying as expected and I eventually hit Control-C. I get ...
6
votes
2answers
9k views

Using setfacl to allow group members to write to any file in a directory

I'd like to use setfacl so that anyone in group 'app' can edit any file contained within /usr/local/users/app regardless of what the traditional UNIX permissions say. I have two users john and ben. I ...
5
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3answers
501 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?
4
votes
3answers
2k views

Permissions issues for shared directory on a server

The setup is we have a VPS running Debian Squeeze, and I've set up a shared directory for us to share files. So far I've followed this guide: ...
3
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3answers
90 views

Can a file be edited with the 'write' permission on it but not on its parent directory?

Suppose the owner/user doesn't have the write permission on a directory but he has it on a file under it. Can the file here be edited or not? If yes, is there any situation where the file cannot be ...
3
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2answers
91 views

Permissions to change only directory content and not itself

We have a directory and want to protect that from remove and rename, but we need to be able to rename, remove and create contents. What we can do?
3
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2answers
401 views

Permissions of webserver's root directory

I've had this issue on several setups, and I'm unsure of how to handle it. At first, all of /var is owned by root:root. Clearly I don't want the web directory to be owned by root, so I do chown ...
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4answers
458 views

USB 500GB external drive mounted with undetermined permissions, missing data

Note: This situation is evolving. Please see the output at the end of this question for the current situation. I'm using Linux Mint 14. Recently, I repartitioned one of my hard drives, and I backed ...
0
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2answers
437 views

setfacl access issues

I have a list of users (user1,user2,user3,superuser). user1, user2 and user3 belong to a usergroup called normalusers . Now, I need to issue the access control list command for the user superuser to ...
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votes
3answers
12k views

How to check which Apache group I can use for the web server to write?

I'm trying to make Wordpress work. I currently have this error message: Could not create directory. /var/www/html/wp-content/upgrade/theme_name when trying to upload a theme. This is the ...
3
votes
2answers
188 views

Back up and restore file permissions

Is there a way to back up and restore file ownership and permissions (the things that can be changed with chown and chmod)? You can do this in Windows using icacls. What about access control lists?
3
votes
2answers
588 views

How does the 'passwd' command gain root user permissions?

How does Linux know that it has to give euid 0 (uid of root) to only certain process like passwd, setuid, etc. If a process can gain root permissions, will it not lead to potential security breaches ...
3
votes
1answer
1k views

Can't rename a directory that I own

I have a directory with a big load of sub directories. I own all of them, and the permissions are all 777. pascal@azazel /box $ ls -al total 147872 drwxr-xr-x 293 root root 12288 aoû 22 19:44 ...
2
votes
2answers
61 views

Who should own files shared by a group and where should they go

I am configuring a Linux work station that will be used by a small number of users (20-30). These users will belong to a small set of groups (5-10) with each user belonging to at least one group and ...
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2answers
1k views

How to hide someone else's directories from a user?

I have several folders: /home/user1/ -u user1 -G user1 /home/user2/ -u user2 -G user2 /home/user3/ -u user3 -G user3 I created three users user1, user2, user3. Each user has their own group. Any ...
2
votes
4answers
434 views

Strange file ownership with Ubuntu

Normally we know when we create one file in Linux, the file's owner and group will set with the creator. For example, I have one user, usera, after I execute usera@srv1:$touch 1.txt I will find the ...
2
votes
2answers
3k views

can't change file permission

Whenever I create or copy few shell files to usb storage device, then I am not able to make them executable. If I create test.sh, it's default file permission will be 644, but when I execute ...
2
votes
2answers
826 views

Mount permissions always blocked

How do I authorise my non-root user to manually mount/unmount ALL media on my desktop. I always get denied permission. Media refers to all mountable USB devices and other partitions on my HDD as ...
2
votes
1answer
716 views

pure-ftpd permission denied on external usb drive

I have a sheevaplug PC (Debian installed) that I'm trying to setup my personal FTP server with. So far I was able to set up auto mounting and installed pure-ftpd. I currently have autofs setup to ...
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2answers
104 views

Broken system after chmod -R 644 /

I use debian jessie and I have done one of those bad mistakes and broke my system with a mistyped command and worse mistakes that follow in such situations. Trying to fix some permissions I ...
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2answers
1k views

newgrp and groups assigned via pam_group.so

For convenience reasons I tend to assign special group memberships like floppy, audio, plugdev, video etc. via /etc/security/group.conf (pam_group.so) mechanism instead of adding all users to this ...
0
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0answers
130 views

DD-WRT: /tmp exec permission

After making a simple hello world OpenWrt package I installed it to the /tmp folder on the dd-wrt device. The program shows up in ls /tmp but when I try to execute it, it shows me /tmp/helloworld: ...
0
votes
2answers
190 views

File permissions of file when tranferring from Windows to Unix

When I am uploading a file from windows PC to Unix ,the permissions of file are --wxr----t on unix machine , whereas umask is 0022 .I am not able to understand from where is the file getting ...
0
votes
1answer
767 views

Script with root permission [duplicate]

Possible Duplicate: Redirecting stdout to a file you don't have write permission on I am creating a script to change the brightness of my laptop. I discovered that I can do this using ...
27
votes
6answers
57k views

File permission issues with shared folders under Virtual Box (Ubuntu Guest, Windows Host)

I am using Ubuntu on Virtual Box and I have a folder which is shared between the host (Windows) and the VM (Ubuntu). When I open any file in the share folder in Ubuntu, I can not change it as its ...
18
votes
3answers
6k views

How to “jail” a process without being root?

Were I root, I could simply create a dummy user/group, set file permissions accordingly and execute the process as that user. However I am not, so is there any way to achieve this without being root?
34
votes
3answers
30k views

What are common rights for /tmp ? I unintentionnally set it all public recursively

I have abused sudo. I have created a really really short life temporary directory that I wanted to share between some users for a few hours... and I named this directory /some/path/tmp Unfortunately ...
15
votes
7answers
11k views

What to use to backup files, preserving ACLs?

When using the tar utility to store files in backups one loses the extended ACLs. Is there some commonly used and not hackish solution (like: create a script that will recrate the ACLs from scratch) ...
14
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7answers
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“Symbolic link not allowed or link target not accessible” / Apache on CentOS 6

I've got a brand new CentOS 6 installation, which has a symlink in the document root to my development files: [root@localhost html]# ls -l total 4 -rwxrwxrwx. 1 root root 0 Sep 18 20:16 index.html ...
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2answers
4k views

How do I make a file NOT modifiable?

While logged in, I can do the following: mkdir foo touch foo/bar chmod 400 foo/bar chmod 500 foo Then I can open vim (not as root), edit bar, force a write with w!, and the file is modified! How ...
7
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2answers
859 views

How are file permissions calculated?

Using chmod I could set the permissions for a file, but if the parent ( .. ) directory had conflicting permissions, what would happen? And if I create a new file, using touch or something similiar, ...
10
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4answers
35k views

Which is more widely used: chmod 777 or chmod a+rwx [closed]

Out of the two options to change permissions: chmod 777 file.txt chmod a+rwx file.txt I am writing a document to send out to our customers, detailing that they need to change the file permissions ...