Find file process linux

How to Find Out Who is Using a File in Linux

In this article, we will explain how to find out who is using a particular file in Linux. This will help you know the system user or process that is using an open file.

We can use the lsof command to know if someone is using a file, and if they are, who. It reads kernel memory in its search for open files and helps you list all open files. In this case, an open file may be a regular file, a directory, a block special file, a character special file, a stream, a network file and many others – because in Linux everything is a file.

Lsof is used on a file system to identify who is using any files on that file system. You can run lsof command on Linux filesystem and the output identifies the owner and process information for processes using the file as shown in the following output.

To list user specific opened files, run the following command replace tecmint with the actual user name.

Another important use of lsof is to find out the process listening on a specific port. For example identify the process listening on port 80 using the following command.

Note: Since lsof reads kernel memory in its search for open files, rapid changes in kernel memory may result into unpredictable outputs. This is one of the major downsides of using lsof command.

For more information, look at the lsof man page:

That’s all! In this article, we have explained how to know who is using a particular file in Linux. We have shown how to identify the owner and process information for processes using an open file. Use the feedback form below to reach us for any questions or comments.

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Linux find process by name

Procedure to find process by name on Linux

1. Open the terminal application.
2. Type the pidof command as follows to find PID for firefox process:
   pidof firefox
3. Or use the ps command along with grep command as follows:
   ps aux | grep -i firefox
4. To look up or signal processes based on name use:

pgrep firefox

Linux find process by name using pgrep command

pgrep command looks through the currently running processes and lists the process IDs which match the selection criteria to screen. All the criteria have to match. For example, will only list the processes called sshd AND owned by root user:
$ pgrep -u root sshd
Just look up pid for firefox process:
$ pgrep firefox

How to use ‘ps aux | grep command’

ps command shows information about a selection of the active processes:
$ ps aux
$ ps aux | grep -i ‘search-term’
$ ps aux | grep ‘firefox’
$ ps aux | grep ‘sshd’
OR use the following syntax instead of using egrep command in pipes:
$ ps -fC firefox
$ ps -fC chrome
The -C option asks ps command to select PIDs by command name.

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Using pidof command to grab PIDs for any named program on Linux

The pidof command finds the process id’s (pids) of the named programs such as sshd, firefox and more. For example:
$ pidof sshd
$ pidof firefox
Sample outputs:

A note about top/htop command

To display Linux processes use top command or htop command:
$ top
OR
$ htop

See also

Getting more help

Read the man pages for the following command using man command:
$ man pgrep
$ man pidof
$ man ps

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Linux / UNIX List Open Files for Process

H ow do I list all open files for a Linux or UNIX process using command line options? How can I show open files per process under Linux?

Both Linux and Unix-like operating systems come with various utilities to find out open files associated with the process.

Tutorial details
Difficulty level	Easy
Root privileges	Yes
Requirements	None
Est. reading time	3 minutes

UNIX List Open Files For Process

First use the ps command command to get PID of process, enter:
$ ps -aef | grep $ ps -aef | grep httpd
Next pass this PID to pfiles command under Solaris Unix:
$ pfiles
$ pfiles 3533
See pfiles command documentation> for more information or type the following man command:
% man pfiles

FreeBSD list open files per process

On FreeBSD use the fstat command along with the ps command:
# ps aux | grep -i openvpn # filter outputs using the grep command #
# fstat -p
# fstat -p 1219
We can count open files count for openvpn process as follows using the wc command:
# fstat -p 1219 | grep -v ^USER | wc -l
The -p option passed to the fstat to report all files open by the specified process.

FreeBSD pstat command in action

Linux List Open Files For Process

First you need to find out PID of process. Simply use any one of the following command to obtain process id:
# ps aux | grep OR
$ ps -C -o pid=
For example, find out PID of firefox web-browser, enter:
$ ps -C firefox -o pid=
Output:

To list opne files for firefox process, enter:
$ ls -l /proc/7857/fd
Sample output:

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For privileged process use the sudo command and to count open files use the wc command on Linux as follows:
# Get process pid
sudo ps -C Xorg -o pid
sudo ls -l /proc/$/fd
# Say pid is 9497 for Xorg, then
sudo ls -l /proc/9497/fd | wc -l
We can use bash for loop as follows too:

Listing Open Files on Linux

Using lsof to display the processes using the most file handles

The lsof command list open files under all Linux distributions or UNIX-like operating system. Type the following command to list open file for process ID 351:
$ lsof -p 351
In this example display and count all open files for top 10 processes on Linux operating systems or server:
# lsof | awk ‘‘ | sort | uniq -c | sort -r | head
## force numeric sort by passing the ‘-n’ option to the sort ##
# lsof | awk ‘‘ | sort | uniq -c | sort -r -n | head

• lsof – Run the lsof to display all open files and send output to the awk
• awk ‘‘ – Display first field i.e. process name only
• uniq -c – Omit duplicate lines while prefix lines by the number of occurrences
• sort -r – Reverse sort
• head – Display top 10 process along with open files count

Conclusion

Now you know how to find open files per process on Linux, FreeBSD, and Unix-like systems using various command-line options. See how to increase the system-wide/user-wide number of available (open) file handles on Linux for more information.

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How To Find a File In Linux From the Command Line

Need to know how to find a file in Linux? Well, surprise, surprise, you’re going to need the find command in Linux to scour your directory or file system. The Linux find command can filter objects recursively using a simple conditional mechanism, and if you use the -exec flag, you’ll also be able to find a file in Linux straightaway and process it without needing to use another command.

Locate Linux Files by Their Name or Extension

Typical Linux Find Commands and Syntax

find command expressions look like this:

find command options starting/path expression

The options attribute controls the behavior and optimization method of the find process. The starting/path attribute defines the top-level directory where the find command in Linux begins the filtering process. The expression attribute controls the assessments that scour the directory tree to create output.

Let’s break down a Linux find command where we don’t just want Linux find file by name:

find -O3 -L /var/www/ -name «*.html»

It enables the top-level optimization (-O3) and permits find to follow symbolic links (-L). The find command in Linux searches through the whole directory hierarchy under /var/www/ for files that have .html on the end.

Basic Examples

1. find . -name thisfile.txt

If you need to know how to find a file in Linux called thisfile.txt, it will look for it in current and sub-directories.

2. find /home -name *.jpg

Look for all .jpg files in the /home and directories below it.

3. find . -type f -empty

Look for an empty file inside the current directory.

4. find /home -user randomperson-mtime 6 -iname «.db»

Look for all .db files (ignoring text case) that have been changed in the preceding 6 days by a user called randomperson.

Options and Optimization for Find Command for Linux

find is configured to ignore symbolic links (shortcut files) by default. If you’d like the find command to follow and show symbolic links, just add the -L option to the command, as we did in this example.

find can help Linux find file by name. The Linux find command enhances its approach to filtering so that performance is optimised. The user can find a file in Linux by selecting three stages of optimisation-O1, -O2, and -O3. -O1 is the standard setting and it causes find to filter according to filename before it runs any other tests.

-O2 filters by name and type of file before carrying on with more demanding filters to find a file in Linux. Level -O3 reorders all tests according to their relative expense and how likely they are to succeed.

• -O1 – (Default) filter based on file name first
• -O2 – File name first, then file-type
• -O3 – Allow find to automatically re-order the search based on efficient use of resources and likelihood of success
• -maxdepth X – Search this directory along with all sub-directories to a level of X
• -iname – Search while ignoring text case.
• -not – Only produce results that don’t match the test case
• -type f – Look for files
• -type d – Look for directories

Find Files by When They Were Modified

The Linux find command contains the ability to filter a directory hierarchy based on when the file was last modified:

find / -name «*jpg» -mtime 5

find /home/randomuser/ -name «*jpg» -mtime 4

The initial Linux find command pulls up a list of files in the whole system that end with the characters jpg and have been modified in the preceding 5 days. The next one filters randomuser’s home directory for files with names that end with the characters “conf” and have been modified in the preceding 4 days.

Use Grep to Find Files Based on Content

The find command in Linux is great but it can only filter the directory tree according to filename and meta data. To search files based on what they contain you’ll need a tool like grep. Take a look:

find . -type f -exec grep «forinstance» ‘<>‘ \; -print

This goes through every object in the current directory tree (.) that’s a file (-type f) and then runs grep ” forinstance ” for every file that matches, then prints them on the screen (-print). The curly braces (<>) are a placeholder for those results matched by the Linux find command. The <> go inside single quotes (‘) so that grep isn’t given a misshapen file name. The -exec command is ended with a semicolon (;), which also needs an escape (\;) so that it doesn’t end up being interpreted by the shell.

Before -exec was implemented, xargs would have been used to create the same kind of output:

find . -type f -print | xargs grep «forinstance»

How to Locate and Process Files Using the Find Command in Linux

The -exec option runs commands against every object that matches the find expression. Let’s see how that looks:

This filters all objects in the current directory tree (.) for files named rc.conf and runs the chmod o+r command to alter file permissions of the results that find returns.

The root directory of the Linux is where the commands that -exec runs are executed. Use -execdir to execute the command you want in the directory where the match is sitting, because this might be more secure and improve performance under certain circumstances.

The -exec or -execdir options will continue to run on their own, but if you’d like to see prompts before they do anything, swap out -exec -ok or -execdir for -okdir.

How To Manage Files Using Plesk?

Let’s say you have a website that’s all ready to go on your laptop/desktop and you’d like to use File Manager to upload it to the Plesk on Linux server:

1. On your machine, you’ll need to take the folder with all of your website’s files on it and add it to a compressed archive in one of the usual formats (ZIP, RAR, TAR, TGZ, or TAR.GZ).
2. In Plesk, go to Files, click the httpdocs folder to open it, click Upload, choose the archive file, and then click Open.
3. As soon as you’ve uploaded it, click in the checkbox you see alongside and then on Extract Files.

How to Edit Files in File Manager

File Manager lets you edit your website pages by default. To do this you can use:

• An HTML editor or a “what-you-see-is-what-you-get” style of editor, which is a nice option because it adds the HTML tags for you. If you aren’t all that confident with HTML then this can be a helpful option.
• Code editor. When you open HTML files with this one you’ll be presented with text where the HTML syntax is highlighted. If you’re comfortable with adding HTML tags yourself then code editor is for you.
• Text editor. HTML files are opened as ordinary text with this one.

Your Plesk administrator may have already et up the Rich Editor extension, in which case you can use it for HTML file editing. Rich Editor works in a what-you-see-is-what-you-get fashion, just like Code Editor, although it’s better specced with features like a spellchecker for instance.

Here’s how to use File Manager to edit a file:

1. Put the cursor over the file and the line that corresponds with it will show a highlight.
2. Open the context menu for the file by clicking on it.
3. Click Edit in … Editor (this will vary depending on your chosen editor).

How to Change Permissions with File Manager

There are some web pages and files that you don’t necessarily want to share with the world, and that’s where altering their permissions settings can come in handy.

To achieve this, find the item you want to restrict Internet access for like this:

1. Place your cursor over it and wait for the highlight to appear as in the previous example.
2. Click on the file to open its context menu and do the same again on Change Permissions.
3. Make your change and then hit OK. If you’d like to find out more about how to look at and alter permissions in Setting File and Directory Access Permissions.

File Manager’s default approach is to change permissions in a non-recursive manner, so consequently, sub-files and directories don’t aren’t affected by the changed permissions of the higher-level directories they belong to. With Plesk for Linux, you can make File Manager modify permissions in a recursive manner, assuming that your Plesk administrator set up the Permissions Recursive extension and that you understand the octal notation of file permissions.

To enable recursive editing of access permissions:

1. Place the cursor over the directory and wait for the highlight.
2. Click to open its context menu and then again on Set Permissions Recursive.
3. Now you can edit them. “Folder Permissions” is talking about the higher-level directory and any of its associated sub-directories. “File Permissions” applies to sub-files in this instance.
4. When you’ve completed your permission amendments, click OK.

File Search in File Manager

You’ve got a little bit of latitude with file searches. You can have File Manager hunt for a specific bit of text either in the file name, in the content, or in both. You can choose how you want it to search for files by clicking on the icon that appears adjacent to your chosen search field, and then clicking on whichever type you prefer.

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