A file system structure in which to store computer files.

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72
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3answers
22k views

Why do directories need the executable (X) permission to be opened?

In my CMS, I noticed that directories need the executable bit (+x) set for the user to open them. Why is the execute permission required to read a directory?
58
votes
1answer
60k views

How to set default file permissions for all folders/files in a directory?

I want to set a folder such that anything created within it (directories, files) inherit default permissions and group. Lets call the group "media". And also, the folders/files created within the ...
50
votes
3answers
13k views

Why hard links not allowed to directories in UNIX/Linux

I read in text books that UNIX/Linux doesn't allows hard links to directories but soft links do. Is it because, when we have cycles and if we create hardlinks, and after some time we delete the ...
48
votes
3answers
2k views

Why does '/' have an '..' entry?

This just baffles me. Why does the root directory contain a reference to a parent directory? bob@bob:/$ ls -a . build home lib32 mnt .rpmdb sys vmlinuz .. cdrom ...
45
votes
4answers
3k views

Pronunciation for /usr directory

How do you pronunce /usr? I found in the net that someone reads it "user"... but, for what I know, this directory is not related to the user. The meaning of the acronym is "Unix specific (or system) ...
38
votes
6answers
4k views

How linux handles multiple path separators (/home////username///file)

I'm working on a python script that passes file locations to an scp subprocess. That's all fine, but I'm in a situation where I may end up concatenating a path with a filename such that there's a ...
35
votes
3answers
1k views

cd by just typing the directory's name?

I either had this somewhere 20 years ago or I dreamed about it. Basically: If if type blobblob I get blobblob: command not found Fair enough. I would like it so that when my shell gets those ...
32
votes
6answers
3k views

The result of ls * , ls ** and ls ***

I know using the command ls will list all the directories. But what does the ls * command do ? I used it and it just lists the directories. Is the star in front of ls means how deep it can list the ...
32
votes
5answers
14k views

Difference between /bin and /usr/bin

I read this up on this website and it doesn't make sense. http://rcsg-gsir.imsb-dsgi.nrc-cnrc.gc.ca/documents/basic/node32.html When UNIX was first written, /bin and /usr/bin physically resided ...
32
votes
2answers
1k views

Why is '.' a hard link in Unix?

I've seen many explanations for why the link count for an empty directory in Unix based OSes is 2 instead of 1. They all say that it's because of the '.' directory, which every directory has pointing ...
30
votes
7answers
6k views

What does the .d stand for in directory names?

I know many directories with .d in their name: init.d yum.repos.d conf.d Does it mean directory? If yes, from what does this disambiguate? UPDATE: I've had many interesting answers about what the ...
26
votes
3answers
2k views

What does size of a directory mean in output of 'ls -l' command?

What does size of a directory mean in output of ls -l command?
24
votes
2answers
5k views

How can I calculate the size of a directory?

How to know the size of a directory? Including subdirectories and files.
23
votes
5answers
9k views

How can I create a /dev/null-like “blackhole” directory?

I would like to create a "/dev/null" directory (or a "blackhole" directory) such that any files written to it are not really written, but just disappear. I have an application that writes out large ...
23
votes
1answer
3k views

Why was '.' chosen to represent the current directory and '..' for parent directory?

After reading this question Design question: Why was '~' chosen to represent the home directory?, next obvious question on my mind was why '.' and '..' was used to represent current directory ...
21
votes
8answers
12k views

How do I get the MD5 sum of a directory's contents as one sum?

The md5sum program does not provide checksums for directories. I want to get a single MD5 checksum for the entire contents of a directory, including files in sub-directories. That is, one combined ...
21
votes
3answers
5k views

Why unix mv program doesn't need -R (recursive) option for directories but cp does need it?

This is a kind of "wtf?" question, so I'm sorry if I will disturb someone's vision of how things should be or if I will just annoy you with the "stupid" question. I always get messed up when need to ...
20
votes
4answers
813 views

Is there any way attacker could use mkdir to compromise a system?

I'm setting up a restricted user account for user ricardo, a troublesome user on my system. I want to grant him the right to make directories using sudo, which he sometimes needs to do. I'm ...
20
votes
9answers
1k views

What's the most resource efficient way to count how many files are in a directory?

CentOS 5.9 I came across an issue the other day where a directory had a lot of files. To count it, I ran ls -l /foo/foo2/ | wc -l Turns out that there were over 1 million files in a single ...
20
votes
8answers
4k views

How do I loop through only directories in bash?

I have a folder with some directories and some files (some are hidden, beginning with dot). for d in *; do echo $d done will loop through all files, but I want to loop only through directories. ...
19
votes
2answers
1k views

Where do the files go if you mount a drive to a folder that already contains files?

I just accidentally mounted a new drive to a folder that already contained files. I don't care about them and have them somewhere else, but that folder appears empty now. I'm curious what happened ...
19
votes
5answers
12k views

How to XZ a directory with TAR using maximum compression?

So I need to compress a directory with max compression. How can I do it with xz? I mean I will need tar too because I can't compress a directory with only xz. Is there a oneliner to produce e.g. ...
19
votes
4answers
14k views

What is the 'working directory' when cron executes a job

I have a script that works when I run it from the command line, but when I schedule it with cron I get errors that it cannot find files or commands. My questions is twofold: When I schedule a cron ...
18
votes
2answers
9k views

Do the parent directory's permissions matter when accessing a subdirectory?

If I have a root folder with some restrictive permission, let's say 600, and if the child folders/files have 777 permission will everybody be able to read/write/execute the child file even though the ...
17
votes
3answers
3k views

How to remove all empty directories in a subtree?

How can I remove all empty directories in a subtree? I used something like find . -type d -exec rmdir {} 2>/dev/null \; but I needs to be run multiple times in order to remove directories ...
17
votes
5answers
3k views

What's the most “correct” mount point for a permanent NTFS partition?

I have an NTFS partition (containing a Windows installation from which I dual boot) that I would like to permanently mount from my Linux installation. Problem is, I can't figure out what the ...
16
votes
6answers
2k views

Why do I have to cd out of a deleted directory?

On my server I have a directory structure looking something like this: /myproject/code I normally have an ssh connection to the server and 'stand' in that directory: root@machine:/myproject/code# ...
15
votes
6answers
2k views

Any way to sync directory structure when the files are already on both sides?

I have two drives with the same files, but the directory structure is totally different. Is there any way to 'move' all the files on the destination side so that they match the structure of the ...
14
votes
3answers
4k views

Is there any way to prevent deletion of certain files from user owned directory?

Let's say user has Directory1 and it contains File1 File2 CantBeDeletedFile How to make so the user would never be allowed to delete the CantBeDeletedFile? If I change the ownership of Directory1 and ...
13
votes
3answers
3k views

When should I use a trailing slash on a directory? [duplicate]

Possible Duplicate: How linux handles multiple path separators (/home////username///file) Most commands I use in linux behave exactly the same whether I include the trailing slash / ...
13
votes
5answers
15k views

Script to monitor folder for new files?

How do I detect new files in a folder with a bash script? I would like to process the files as soon as they are created in the folder. Is this possible to do so or do I have to schedule a script with ...
12
votes
4answers
7k views

Converting relative path to absolute path

Is there a *nix command to get absolute(and canonicalized) path from relative path(with current path) or symbolic link?
12
votes
1answer
632 views

How to find all the links to a directory

When I stat a directory I get a listing that tell me there are 5 links to the directory. stat dir My question is how do I get information (names and locations) to all these 5 links?
11
votes
4answers
744 views

How do I choose specific files in a different directory using bash?

I want to list (or delete, or do some other operation) on certain files in a directory, like this: $ ls /opt/somedir/ aa bb cc aa.txt bb.txt cc.txt $ ls /opt/somedir/(aa|bb|cc) ## pseudo-bash ...
11
votes
3answers
2k views

Flattening a nested directory

This is probably very simple, but I can't figure it out. I have a directory structure like this (dir2 is inside dir1): /dir1 /dir2 | --- file1 | --- file2 What is ...
11
votes
1answer
204 views

How to log all the events performed on directory?

How can I log all the events performed on a particular directory? I want to log the entry of each directory modified within some time duration. I am using find . -type d -mmin -5 command. In ...
10
votes
4answers
1k views

Best method to collect a random sample from a collection of files

Suppose there is a directory holding 300 data files. I want to randomly select 200 of those files and move them into another directory. Is there a way to do that under Unix/Linux?
10
votes
2answers
781 views

How can I copy a file and create the target directories at the same time?

I want to cp aaa/deep/sea/blob.psd to bbb/deep/sea/blob.psd How do I do the copy if the deep and sea directories don't exist under bbb so that the copy both creates the directories that are needed ...
10
votes
4answers
779 views

Include / in symlink to a directory?

Symlinking to a directory gives to different results with ls -l depending on whether I ln -s dir or ln -s dir/. But what's the actual difference, and which one should I prefer why?
9
votes
5answers
3k views

Creating numerous directories using mkdir

I would like to create many directories using mkdir. Each directory name will consist of a prefix (a string) and an index (an integer). Suppose that I would like the prefix to be "s" and the indices ...
9
votes
4answers
3k views

symbolic link to a directory and relative path

I've created symlink with absolute path to the directory (Blink) and have for example following tree: $ ls -l /tmp/A total 0 lrwxrwxrwx 1 root root 6 Apr 3 12:27 Blink -> /tmp/B -rw-r--r-- 1 root ...
9
votes
1answer
2k views

Create a symbolic link relative to the current directory

I'm trying to create a symbolic link in my home directory that points to a directory on my external HDD. It works fine when I specify it like this: cd ~ ln -s /run/media/name/exhdd/Data/ Data ...
9
votes
4answers
33k views

“Input/output error” when accessing a directory

I want to list and remove the content of a directory on a removable hard drive. But I have experienced "Input/output error": $ rm pic -R rm: cannot remove `pic/60.jpg': Input/output error rm: cannot ...
9
votes
2answers
2k views

games directory?

On a standard filesystem, we have: /usr/games /usr/lib/games /usr/local/games /usr/share/games /var/games /var/lib/games Is this a joke, or is there some history behind this? What is it for? Why do ...
9
votes
3answers
743 views

Lowercasing all directories under a directory

I want to lowercase every directories' name under a directory. With which commands can I do that?
8
votes
3answers
893 views

what is wild card to select all directories in a directory

i want to set sticky bit for all directories in a directory excluding files. is there any wild card to do this? #sudo chmod g+s /var/www/<WILD_CARD_FOR_ALL_DIRECTORIES>
8
votes
5answers
1k views

Bash CD up until in certain folder

I do a lot of work in Magento, and so do a lot of the people I work with, and it gets annoying to have to type: cd ../../../../../../ To only find you're still a few directories from your root ...
8
votes
6answers
637 views

Best way run a command on each file in a directory tree

There appear be a number of ways to do this including loops in shell script, find and xargs. Which of these is best, and which is most portable?
8
votes
4answers
2k views

How are directories implemented in Unix filesystems?

My question is how directories are implemented? I can believe a data structure like a variable e.g. table, array or similar. Since UNIX is Open Source I can look in the source what the program does ...
8
votes
3answers
337 views

What are ./ and ../ directories?

Simple question, but I'm not sure where to look and google doesn't respond to periods and slashes. I'm just trying to count the # of files & directories in the current directory (not including ...