Use this tag for questions about file management and operations on files.

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0
votes
0answers
103 views

How do I recover a file with vim?

I am trying to recover my sudoers file. I typed in my Chrome OS terminal vim -r /etc/sudoers After that it gave me the following, Swap files found: Using specified name: 1. .sudoers.swm ...
78
votes
16answers
24k views

Is there an easy way to replace duplicate files with hardlinks?

I'm looking for an easy way (a command or series of commands, probably involving find) to find duplicate files in two directories, and replace the files in one directory with hardlinks of the files in ...
73
votes
2answers
111k views

Empty the contents of a file

I am aware of three methods to delete all entries from a file. They are >filename touch filename filename < /dev/null Of these three I abuse >filename the most as that requires the ...
65
votes
6answers
185k views

How to get over “device or resource busy”?

I tried to rm -rf a folder, and got "device or resource busy". In Windows, I would have used LockHunter to resolve this. What's the linux equivalent? (Please give as answer a simple "unlock this" ...
45
votes
4answers
29k views

Clone ownership and permissions from another file?

Is there a command or flag to clone the user/group ownership and permissions on a file from another file? To make the perms and ownership exactly "like" that of another file?
20
votes
7answers
38k views

Test if there are files matching a pattern in bash

I am trying to write an if statement in bash to test whether there are any files matching a certain pattern. If there is a text file in a directory it should run a given script. My code currently if ...
28
votes
3answers
76k views

Sort based on the third column

I'm facing a huge 4-columns file. I'd like to display the sorted file in stdout based on its 3rd column: cat myFile | sort -u -k3 Is that enough to perform the trick?
6
votes
1answer
225 views

Have a 'file' generate its content on demand? [duplicate]

Is there a way that I can have something which appears as a file, but when being read some code executes which fills the content of the file "on the fly"? Like FIFO/ named pipe, but without the need ...
20
votes
3answers
14k views

Determining if a file is a hard link or symbolic link?

I'm creating a shell script that would take a filename/path to a file and determine if the file is a symbolic link or a hard link. The only thing is, I don't know how to see if they are a hard link. ...
14
votes
3answers
12k 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, ...
9
votes
6answers
1k views

Modify a file without creating another file

Is there a way to modify a file without writing the contents to another file, without sed and awk? For example: $ cat test.txt aaa aaa bbb ccc ddd Replacing using sed with -i option, sed -i ...
9
votes
4answers
11k views

Renaming a bunch of files with date modified timestamp at the end of the filename?

So, say, I have a directory with a bunch of files like g.txt, where g.txt was last modified on, say, June 20, 2012. How would I batch-rename all of the files (like g.txt) with the last modified date ...
9
votes
4answers
7k 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 ...
32
votes
7answers
3k views

Is it a UUOC (useless use of cat) to redirect one file to another?

If I want to make the contents of file2 match the contents of file1, I could obviously just run cp file1 file2. However, if I want to preserve everything about file2 except the contents—owner, ...
10
votes
5answers
16k views

How to remove blank lines from a file in shell?

I want to remove all empty lines from a file. Even if the line contains spaces or tabs it should also be removed.
8
votes
3answers
24k views

List of Recently Modified Files

How can I Get a list of all files modified , say 3 months ago. I checked this question but I was not able to apply it to my scenario. I am trying this now , it seems to be working , but I know there ...
8
votes
2answers
7k views

Group member cannot write even with write permission

The logged in user is a member of a group that has a write permission on a folder. But when this user is trying to write something, "permission is denied". The log below summarizes the question: ...
7
votes
3answers
525 views

How can I make a special file that executes code when read from [duplicate]

Most files on a Linux system are normal files, i.e. they are saved on disk and reading from them just reads from a specified chunk of memory on the disk. How can I make something that behaves like a ...
7
votes
4answers
10k views

Understanding of diff output

I have file1.txt this is the original text line2 line3 line4 happy hacking ! and file2.txt this is the original text line2 line4 happy hacking ! GNU is not UNIX if I do: ...
5
votes
1answer
4k views

Automatically detect when a file has reached a size limit

I would like to send an email when a file reach a certain size limit. The only way I thought of doing this is by doing a cronjob which will check the file size and send the email if the file is ...
10
votes
8answers
613 views

sed in-place line deletion on full filesystem?

Due to an application bug as yet undiagnosed, I have several hundred servers with a full disk. There is one file that has been filled up with duplicate lines—not a log file, but a user environment ...
9
votes
3answers
2k views

How to copy a directory recursively using hardlinks for each file

I want to create a "copy" of a directory tree where each file is a hardlink to the original file Example: I have a directory structure: dirA/ dirA/file1 dirA/x/ dirA/x/file2 dirA/y/ dirA/y/file3 ...
8
votes
2answers
715 views

Cleaner way to delete files on Linux which include a datestamp as part of file name

I have a new requirement to purge MySQL dump files that are older than 30 days. The files use a naming convention of "all-mysql-YYYYMMDD-HHMM.dump". The files are located on SAN mounted file system, ...
6
votes
2answers
6k views

“no such file or directory” message when deleting a file that exists on NTFS

I have a directory with images. Suddenly I found out that there's a new image with a new name. The image content is similar to another image in another directory but with a different name. I didn't ...
5
votes
2answers
1k 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
4answers
10k views

get age of given file

How can I get the age of a given file in, at least, days? I'm well aware of ls -lh and similar commands. I want something that will work sort of like this: getfage <FILE> # prints out '12d' ...
4
votes
2answers
2k views

Access history of a file [duplicate]

I was wondering if there are any tools to keep track of the access history of a file. I know of stat, but as far as I understand, it only returns information about the last time the file was accessed. ...
3
votes
4answers
441 views

Determining the number of files and subdirectories in Linux

When displaying directories in linux using ls -ld, I get something like this: user@shell:~/somedirectory$ ls -ld drwxr-xr-x 2014 K-rock users 65536 20011-11-05 11:34 user@shell:~/somedirectory$ ...
3
votes
2answers
362 views

Outputting common lines from 2 files and uncommon lines from both the files in one output file

I have 2 text files. Lets name them file1.txt and file2.txt file1.txt is as follows chr10 181144 225933 chr10 181243 225933 chr10 181500 225933 chr10 226069 255828 chr10 255989 267134 ...
59
votes
4answers
19k views

locate vs find: usage, pros and cons of each other

In Linux and Unix systems there are two common search commands: locate and find. What are the pros and cons of each? When one have benefits over the other?
69
votes
9answers
112k views

How can I get the size of a file in a bash script?

How can I get the size of a file in a bash script? How do I assign this to a bash variable so I can use it later?
47
votes
7answers
4k views

How are file types known if not from file suffix?

I would like to know how file types are known if filenames don't have suffixes. For example, a file named myfile could be binary or text to start with, how does the system know if the file is binary ...
20
votes
5answers
207k views

How to create a simple .txt (text) file using terminal? [closed]

I'm just trying to review basic terminal commands. Having said that, how do I create a text file using the terminal only?
34
votes
6answers
7k views

How does Linux choose which application to open a file?

If a file tells the OS its file format, how does the OS choose which application to open it by default? In Windows, is the association stored in the registry table? How does Linux choose which ...
27
votes
4answers
16k views

How to properly and easy configure `xdg-open` without any enviroment?

I'm using OpenBox window manager without any desktop enviroment. xdg-open behaves strangely. It opens everything with firefox. $ xdg-settings --list Known properties: default-web-browser ...
20
votes
3answers
80k views

undelete a just deleted file on ext4 with extundelete

Is there a simple option on extundelete how I can try to undelete a file called /var/tmp/test.iso that I just deleded? (it is not so important that I would start to remount the drive read-only or ...
20
votes
2answers
21k views

What does the 'd' mean in ls -al results and what is that slot called? [duplicate]

In Linux, what does the d mean in the first position of drwxr-xr-x? And what are all of the possible letters that could be there, and what do they mean? I'm trying to learn more about the Linux file ...
19
votes
5answers
18k views

How to copy directories with preserving hardlinks?

How to move directories that have files in common from one to another partition ? Let's assume we have partition mounted on /mnt/X with directories sharing files with hardlinks. How to move such ...
17
votes
2answers
23k views

Fastest way to concatenate files

I've got 10k+ files totaling over 20GB that I need to concatenate into one file. Is there a faster way than cat input_file* >> out ? The preferred way would be a bash command, Python is ...
45
votes
2answers
4k views

Why is rm allowed to delete a file under ownership of a different user?

From the post Why can rm remove read-only files? I understand that rm just needs write permission on directory to remove the file. But I find it hard to digest the behaviour where we can easily delete ...
15
votes
3answers
19k views

Quickly find which file(s) belongs to a specific inode number

I know of this command: find /path/to/mountpoint -inum <inode number> but it is a very slow search, I feel like there has to be a faster way to do this. Does anybody know a faster method?
13
votes
2answers
521 views

How can I be sure that a directory or file is actually deleted?

I know that most files, when deleted, aren't actually removed from the disk, and can be recovered later. How can I ensure that a directory I had deleted will actually be removed from the disk? Are ...
4
votes
5answers
12k views

Count files in a directory by extension

For the purpose of testing, I'd like count how many images files are inside a directory, separating each image file type by file extension (jpg="yes". This because later it will be useful for another ...
12
votes
3answers
48k views

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 ...
9
votes
2answers
45k views

Cron job to delete files older than 3 days

I need to remove files older than 3 days with a cron job in 3 different directories. (these 3 directories are children of a parent directory /a/b/c/1 & /a/b/c/2 & /a/b/c/3) Can this be done ...
5
votes
3answers
3k views

How is it possible to do a live update while a program is running?

I wonder how killer applications such as Thunderbird or Firefox can be updated via the system's package manager while they are still running. What happens with the old code while they are being ...
3
votes
4answers
1k views

What command do I use to see the start and end block of a file in the file system?

Is there any command that will output the beginning and ending blocks of any file?
13
votes
2answers
1k views

Is that possible to integrate zip and tar.gz files as directory into the file system

I wonder if there is a way to integrate (it's a bit different from mounting, I think) compressed files as directories into the file system? E.g., one could download a compressed-file.tar.gz to his ...
9
votes
1answer
10k views

How to change the default program for a specific file extension system-wise in kde or xfce?

I'd like to have certain file extensions to be opened with some specific programs. What are the files the edit ? I have found in /usr/share/appplications/default.list but it doesn't work.
8
votes
2answers
9k views

How to circumvent “Too many open files” in debian

If I want to see all relevant log files of my apache2 server at once, I use tail -f /var/kunden/logs/*log /var/kunden/logs/*log /var/log/apache2/*log |grep -v robots|grep -v favicon But since those ...