procfs (or the proc filesystem) is a special filesystem in UNIX-like operating systems that presents information about processes and other system information in a hierarchical file-like structure

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/proc/net/wireless does not show values unless run as root

cat /proc/net/wireless does not show statistics for wireless devices unless it is run as root, even though the permissions on the file are 444. The same seems to apply when accessing statistics via ...
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429 views

How to get environmental variables of a very short process?

I have a very short process for which i want to check the environmental variables for debugging purposes. The process is instant from a human perspective. The example illustrates it better. Example ...
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205 views

How to print total number of file descriptors with index 24

How can I print the total number of file descriptors with index 24 for all the running processes on Linux? I tried $ ls /proc/*/fd 2> errors.txt > stdout.txt | grep "^24" stdout.txt | wc -l ...
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1answer
205 views

Why is one file listed sereval times in /proc/pid/smaps?

When I cat /proc/1/smaps file I found that libs have often up to 4 mappings with different sizes and different Rss/Pss etc: 7f1a09696000-7f1a0982f000 r-xp 00000000 fe:04 1313975 ...
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600 views

In Linux, why do you need to be root to write to /proc/sysrq-trigger?

WARNING: THE NEXT KEY COMBINATION WILL CRASH YOUR COMPUTER Ok, I get that this is an administrative tool and all, but I realized that any user can do ALT + SysRq + C. This link explains what I'm ...
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No /proc in a Busybox-based embedded Linux distribution

I am making an embedded Linux distribution and my board is a Raspberry Pi. My kernel version is 3.2.27 without initramfs and my root file system as follows: /lib /* contains ...
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1answer
477 views

CPU speed and cat /proc/cpuinfo

I use centos 6.4 64. I have old proc - CPU AMD Phenom II X4 810 (HDX810W) 2.6 GHz. However, when I execute the command cat /proc/cpuinfo I get the following: processor : 0 vendor_id : ...
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564 views

how to read any process' /proc/pid/io

I'm trying to monitor disk activity of each process. One way that I found how to do this is to read /proc/pid/io file and compare fields with previous read. That works fine except my monitoring ...
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613 views

System IDLE Time > System Uptime?

I was testing out the linux api while working on something but got stuck on the following output. [Abhii@localhost net]$ cat /proc/uptime 39135.53 149657.73 As per specs the first number should be ...
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772 views

Is there a utility that interprets /proc/interrupts data in time?

is there something out there ? Like top is for ps
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50 views

Is there any way to hide kernel threads from ps command results?

When I type ps -ef , there are lots of special kernel thread processes showing. I am not interested in kernel threads; I am only interested in user process/thread. Is there a way that I can hide the ...
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7k views

how to determine the max user process value?

Which value is correct?(or they are all correct, but which one will take effect?) $ cat /proc/sys/kernel/pid_max 32768 $ ulimit -a |grep processes max user processes (-u) 77301 $ cat ...
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279 views

Detecting kernel thread on pre-3.0 kernels

Looking at the proc man page (http://man7.org/linux/man-pages/man5/proc.5.html) it is possible to detect which processes are kernel threads in /proc/<pid>/stat by looking at the flags value ...
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2k views

File delete versus overwrite and link at /proc/pid/fd

It is well known that UNIX systems won't actually delete a file on disk while the file is in use. So if a file is being accessed by process 1 and process 2 deletes the file using rm, process 1 ...
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27 views

Utility which gives line from /proc/id/maps by specific address

Is there an utility that gives me specific line from /proc/id/maps when given specific address from this process? For example when given 0x7fb4a84f6008 it returns: 7fb4a84f6000-7fb4a84fd000 r-xp ...
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478 views

Dirty in /proc/meminfo for dd

I read from here that the below command gives me the amount of data that needs to be written to the disk. grep ^Dirty /proc/meminfo It particularly says Ever ask yourself "How much data would be ...
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Is there a way to identify which process turns into Zombie process

One of the ubuntu server has 82 zombie processes. All processes shows '[sh] defunct' as process command. Is there a way to find out which process is becoming a zombie process? I tried checking the ...
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1answer
3k views

parsing process ID/names from /proc, thread IDs

When I'm parsing process IDs from /proc, obviously each thread of a process gets its own ID. And I realize that all the threads in that same process can be gathered from /proc/${pid}/task/. But my ...
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31 views

What happened to /proc/sys/fs/relatime_interval?

According to one answer relatime interval can be changed by echo 60 > /proc/sys/fs/relatime_interval but I do not have such a file? Where did it go? $ ls /proc/sys/fs aio-max-nr ...
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1answer
73 views

How do I find out more about socket files in /proc/fd?

Looking in /proc/$mypid/fd/, I see these files lrwx------ 1 cm_user cm_user 64 Oct 14 03:21 0 -> /dev/pts/36 (deleted) lrwx------ 1 cm_user cm_user 64 Oct 14 03:21 3 -> socket:[1424055856] ...
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1answer
371 views

lsof: measure I/O rate of a socket fd

I'm writing a script that parses the output of lsof to show a list of what processes have sockets open (similar to what netstat shows). lsof also gives me a file descriptor. What I want to do now is ...
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1answer
3k views

The amount of time since the system was last booted [duplicate]

I have used both uptime and cat /proc/uptime commands. I know the idle time in the later can be greater than running time (multiprocessors). However, when I add both running and idle times, and ...
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2k views

Busybox ash script does not exit cleanly after executing cat; unable to get exit code

Consider the following script wrapcat.sh (a wrapper for cat) for illustrative purposes. It is run with busybox (ash) in an embedded Linux 2.6 box. #!/bin/sh cat $1 Under certain circumstances, this ...
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3answers
695 views

files in /proc/$PID (e.g. ssh-agent, Chrome) are not owned by user but by root

I am just answering another question here :-) and thus had a look – wanted to have a look at /proc/$PID/fd of ssh-agent in order to find out which socket it uses. But I can't. I am quite surprised to ...
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633 views

What is the connection between jiffies and IPS? How to convert jiffies to IPS?

Reading from /proc/PID/stat a lot of information can be processed. I would like to see how many percentages has been used of CPU power by this process. There are a lot of variable around here (utime, ...
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1answer
47 views

Why is the size of “/proc/kcore” file so bigger than the physical memory size?

From proc manual: /proc/kcore This file represents the physical memory of the system and is stored in the ELF core file format. With this pseudo-file, and an unstripped kernel ...
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180 views

Portable way to parse /proc/meminfo

I'm having trouble finding a generic code that work, here, for both CentOS 5/6 and CentOS 7 versions pc the /proc/meminfo file. I Want to compute the "Real Used memory" like free does. (amounts ...
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195 views

Disk I/O latency using /proc/vmstat file

How do I calculate disk read and write latency in Linux? Is it possible to do the calculation using /proc file system? I am using iostat and vmstat command. But I do not understand how the ...
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29 views

Significance of Linux kernel's default_console_loglevel

What is the significance of default_console_loglevel in Linux? Commonly I see it described as the default value of console_loglevel. However, what that means I haven't seen explained anywhere. ...
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262 views

Monitor the creation of new processes

I want to get a notification whenever a new process is created. I've tried to use inotify on /proc, but it didn't report any event even though a new directory appeared in /proc. I could list the ...
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52 views

What are the /proc/drivers directories organisation for nouveau or radeon

The context: I need to get some basic informations from the graphic card in a lib in lua. The idea is to not rely on external software (like hwinfo for example). I know that for a system with an ...
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1answer
293 views

Programmatically get CPUs 'detailed' usage, like top/htop

htop has a great way to show CPU usage. It shows the activity (usage in %) of each cores, and each core gauge is divided into three parts : blue: low priority processes green: normal processes red: ...
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141 views

“ps” output and comments

I'm pretty sure you cant do this but maybe someone has some weird hack... Is there a way to get comments (#blahblah) to show up in ps output? My problem is that i have a script, lets call it ...
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761 views

How can I disable /proc pseudo-filesystem on a shared Linux environment?

Is it possible to disable the /proc pseudo-filesystem to prevent w, ps, top, etc, from showing what other users are doing? Of course, I still want "everything else" to work correctly. Is there a ...
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4k views

Using /proc/stat for the number of processes running on the system

How does one find out the true number of processes that is running on your system. A number of articles mention using ps in order to count the number of processes. But recently I looked at cat ...
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437 views

Making Bootable USB, problems copying /proc

I'm creating a bootable usb as a cloned partition and am running into problems copying /proc to the usb. I know /proc contains a lot of virtual files, but I'm not sure how to copy them over. It seems ...
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256 views

Read “/proc” to know if a process has opened a port

I need to know if a process with a given PID as opened a port without using external commands. I must then use the /proc filesystem. I can read the /proc/$PID/net/tcp file for example and get ...
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92 views

How can I wake a process from sleep status via signal or /proc?

Many years ago I had an issue with Linux where processes would randomly go to sleep. Back then, I knew a trick with the /proc filesystem to trigger a wakeup of the process. I vaguely remember being ...
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97 views

Wrong eUID in `/proc/PID/status` when SETUID is used

While doing a wargame challenge, I ran into an issue with permissions. The info given by /proc/PID/status is not in adequation with the permissions that should be given to the processus. I am user ...
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1answer
27 views

Encoding of /proc/<pid>/cmdline files

I am thinking about working with the /proc/<pid>/cmdline files, but I couldn't find any documentation about the file encoding. The only piece of information I could find is located in the man ...
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1answer
124 views

Memory usage of a given process (using Linux proc filesystem)

I want to know which files from /proc directory and which fields of these files I need to calculate the memory usage of a given pid. I've been using the "stat" file and the "vsize" parameter that is ...
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31 views

Directory in /proc that isn't process dir but start with number?

Quick question. Is it possible to create directory in /proc that starts with number but isn't process directory (where name is PID)? I write software that searches for process directories and I wonder ...
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2answers
93 views

List running processes without procfs

I'd like to list running process (like using ps or top), but there is no procfs mounted. The procfs not being mounted is intentional, and is made to prevent malicious user to access systems ...
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2answers
1k views

With “find /”, skip directories like “/proc”, “/sys” and similar [duplicate]

There are some directories that can cause problem with find, and especially find /. These are directories in which the OS creates files which are not really files. Among these directories are /proc ...
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224 views

Looking for /procfs documentation, describing values and units of measurement

Surprisingly, comprehensive documentation for /procfs is hard to find. For my specific question, I am looking at: cat /proc/1/statm (let's use pid=1 because it seems to be always there). I just ran ...
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30 views

What is /proc/dma? Is it just for legacy support?

I reading a Linux book that told me I can check the dma channels by reading /proc/dma. This is what I see when I run cat /proc/dma: 2: floppy 4: cascade I'm confused because that looks like old ...
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168 views

How to get UID and PID

So here's what I want to do: User inputs a USERNAME. Based on this username, I need to get the list of processes started by this user. I am planning to do this by getting the UID of this user and ...
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1answer
2k views

Do VmPeak & VmHWM have any measurement periods?

While reading kernel documentation I came across VmPeak & VmHWM, and it's a bit unclear to me. VmPeak in /proc/<pid>/status is described to be peak virtual memory size. Peak for what ...
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1answer
14k views

Modify 'Soft Limit' of 'Max processes'

I tried ulimit -u 2000 and ulimit -Su 2000 to modify the 'Max processes', and started up my program, but failed. I found file '/proc/pid/limit' is still: Max processes 1024 ...
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554 views

Ubuntu: /proc/pid/comm file missing

On my development box, under /proc/[pid]/ there is a file called comm containing the name of the executable for that process. I use this to validate the process to which I am sending a signal. On our ...