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

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19
votes
4answers
2k views

Is there an “open with” command for the command line?

Does the command line have a way to get a recommended list of programs used to open a particular file, based on the file type? For example, a .pdf file would have an open with... recommendation using ...
19
votes
3answers
10k views

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

I'm creating a shell script that would take a a filename/path to a file and determines 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 ...
11
votes
3answers
10k 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
4answers
10k 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
6k 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
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: ...
6
votes
3answers
20k 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
682 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
3answers
505 views

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

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 ...
6
votes
2answers
5k 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 ...
6
votes
3answers
2k views

Create a virtual file that is actually a command

Is there any way to create a virtual file, such that reading from the file actually reads from the stdout of a command; writing to the file is acually writing to the stdin of a command? So far I have ...
4
votes
1answer
3k 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 ...
3
votes
4answers
9k 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' ...
7
votes
4answers
8k 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: ...
4
votes
2answers
744 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?
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
387 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$ ...
56
votes
9answers
93k 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 ...
33
votes
6answers
6k 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 ...
26
votes
4answers
14k 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 ...
15
votes
5answers
169k 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?
15
votes
3answers
66k 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 ...
17
votes
2answers
18k 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 ...
57
votes
3answers
191k views

Get file created/creation time? [duplicate]

Possible Duplicate: How do I do a ls and then sort the results by date created? Is there a command in Linux which displays when the file was created ? I see that ls -l gives the last ...
17
votes
5answers
16k 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
3answers
41k views

how to output text to both screen and file inside a shell script?

Currently I have a shell script which logs messages to a log file like this: log_file="/some/dir/log_file.log" echo "some text" >> $log_file do_some_command echo "more text" >> $log_file ...
13
votes
2answers
510 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 ...
13
votes
3answers
16k 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?
4
votes
5answers
10k 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 ...
8
votes
5answers
989 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 ...
7
votes
2answers
38k 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 ...
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
3answers
37k 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 ...
8
votes
2answers
8k 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 ...
4
votes
4answers
2k views

Clone directory tree structure and copy files to the corresponding directories modified after a specific date

I have a folder with more than 30 sub directories and I want to get the list of the files which was modified after a specified date(say sep 8 which is the real case) and to be copied with the same ...
4
votes
3answers
2k 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 ...
2
votes
4answers
527 views

Search and Delete duplicate files with different names

I have a large music collection stored on my hard drive; and browsing through it, I found that I have a lot of duplicate files in some album directories. Usually the duplicates exist alongside the ...
10
votes
4answers
8k views

How do you compare two folders and copy the difference to a third folder?

You've got three folders: folder current, which contains your current files folder old, which contains an older version of the same files folder difference, which is just an empty folder How do ...
10
votes
1answer
13k 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 ...
10
votes
5answers
7k views

Keep log file size fixed without logrotate

Is there any way to keep file size of log file fixed without rotating it by a new empty file and deleting (or archiving) the old file. For example, if I set log file maximum size to 1MB, after the ...
7
votes
5answers
2k views

Delete all files in a directory whose name do not match a line in a file list

I have a directory with 1000+ files. In a text file, I have about 50 filenames, one per line. I'd like to delete all the files in the directory whose filenames don't correspond with an entry on the ...
7
votes
1answer
9k 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.
5
votes
8answers
4k views

Run a command on all subfolders

If you have a series of subfolders (like from a to z) and want to run a command on each one of them (like rm *.pdf or ls *.pdf), how do you do that? The "manual" approach would be cd a, rm *.pdf, or ...
3
votes
1answer
16k views

How to add 'open folder as root' in Elementary OS file manager context menu?

Here it is the solution in order to add the 'open terminal here' into the context menu of Elementary OS' file manager (generically called 'Files' - the executable is pantheon-files). For that ...
3
votes
2answers
2k views

Concatenate specific files into one single file

In a folder containing X files, I need to concatenate Y files (where X > Y) together into a single text file. I have the filenames (of Y files) that I need to concatenate. Can anyone please help me ...
1
vote
4answers
122 views

Changing column of multiple csv files

I have a csv file called scenario1.csv in which the second column has column names like "0-4 years high risk", "65+ years first responder" etc. There are 20 such values. The 21st row, 2nd column has ...
31
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, ...
11
votes
2answers
7k views

Why can't I have a folder and a file with the same name?

I've never had this problem before, but for some reason, I can't rename my folder to packages/. This is the structure: root - packages_old/ - packages When I try to rename the folder with ...
10
votes
8answers
291 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 ...