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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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
390 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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160 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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827 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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9k 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 /proc/...
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460 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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1k 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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157 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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161 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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73 views

How can I check read permission of /proc/*/* files?

Files in /proc/ seem to be world-readable, but return permission denied: $ ls -lh /proc/5589/smaps -r--r--r-- 1 root root 0 Mar 18 13:11 /proc/5589/smaps $ cat /proc/5589/smaps cat: /proc/5589/...
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66 views

Why doesn't INotify work with `/etc/mtab` or `/proc/mounts`? [duplicate]

When I used INotify with /etc/mtab or /proc/mounts, it doesn't detect changes when things mount or unmount, even though /etc/mtab and /proc/mounts both have changed when I check manually. Why is this, ...
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91 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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270 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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394 views

How to read files in the proc directory? [closed]

I found that ls command can't read file in `/proc' Please see the attachment. There are many link files ,but you can't read it by ls.
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2k 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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237 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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37 views

Getting the original command invocation from /proc/self

I'm trying to run some startup code in all procesess via the dynamic linker. The code should do stuff based on the zeroth argument of the process. I'm getting the arguments from /proc/self/cmdline (...
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55 views

Duration of /proc/pid/stat

I have a process that starts a child process and when the child exits, scans /proc/<pid>/stat to gather some information about the CPU and memory the child used. However I am worried that I am ...
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1answer
56 views

Get the process start time irrespective of NTP updates

I'm trying to record the start time of a process kicked off by an @reboot cronjob. I'm using ps -p $$ -o ltime= presently, but I've run into a catch. My machine (a Raspberry Pi) connects to the ...
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110 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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402 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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19k 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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677 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 ...
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1k views

How to clone a read-only portion of /proc file system

The problem with reading /proc file system is that it is not atomic. I tried using a library (procfs in Python) that wishes to read it, but it has glitches about 5% of the time because the process ...
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752 views

vmstat on virtual machine and large values

Hi I'm using vmstat to track machine performance during some tests (jmeter). This is virtual machine running on a big machine where lots of other virtual machines are installed (about 20 virtual ...
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24 views

How to tell if a block device needs cache flushes

I want to know if a particular block device claims to requires cache flushes. From the xfs faq (emphasis mine): Q. Should barriers be enabled with storage which has a persistent write cache? ...
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18 views

Does the format or columns of /proc/dev/net change often?

I'm writing a script to scrape some data from this. I'm wondering if this file changes often or is different between distros.
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42 views

How to obtain counters for swap-in/swap-out on Linux?

I'm trying to obtain counters for swap-in/swap-out activity on CentOS 6. The intention is to feed raw data into RRDtool to generate graphs, and use it to generate alerts. I've had a look at common ...
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1answer
200 views

Unable to read /proc/pid/stack file even with proper permissions

As far as i know, i should be able to read a regular file contents if i have the permissions to do so. Following is the output of ls -l stack for the stack file (/proc/pid/stack) for one of the ...
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221 views

Is there any way to read files from the virtual /proc directory using smbclient?

Is there any way to read files from the virtual /proc directory using smbclient? No root access. Both server and client are Debian Linux machines. Server is running Samba 3. Smbclient version is 4.0....
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246 views

processor(s) statistics that is one day old

I already know how to use grep -w cpu /proc/stat in order to get the cpu stats and identify the user mode. Percentage wise, I just divide it my the total time from the /proc/uptime. However, how can ...
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540 views

Do kernel counters for jiffies in state exist in Linux?

I am looking to get time/jiffie stats on the state of a daemon process. The states I'm referring to are mentioned in the Linux Kernel Proc Filesystem document. Running, Sleeping, uninterruptible sleep,...
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486 views

About sector and blocks, and a little confusion in /proc/diskstats

I've been studying about diskstats lately, and I get that the amount of hdd read comes in sectors. But in most places I've noticed that there exists a slight misunderstanding about sectors and blocks. ...
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1k views

Connecting various process attributes reported by top, ps, /proc/pid/statm, /proc/pid/status, /proc/pid/smaps [closed]

Here are some of the common attributes I figured out: top(VIRT) , smem(VSS), /proc/pid/statm (1st entry in pages), /proc/pid/status (VmSize), ps(VSZ) top(RES) , smem(RSS), /proc/pid/statm (2nd entry ...
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Why remount of /proc/sys is not global or does not persist in network namespace inside LXC

I have host running RHEL-7.2. Inside that running LXC. Inside LXC creating network namespaces. Inside the namespace changing sysctl variables was failing (as root): $ ip netns add testns $ ip netns ...
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54 views

sar command vs /proc/stat for cpu usage

I have been using /proc/stat for calculating the cpu usage. Recently I have been going through sar command for calculating cpu usage. And what I found was that their values were not related (I was ...
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3answers
58 views

Get Linux architecture from /proc filesystem

I'm writing a program in Java and I need to determine the architecture for which Linux was compiled. I need something like uname -m, but without running any program, but instead from the /proc pseduo-...
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75 views

Recover from faking /proc/meminfo

So, without really thinking too much, I ran this script: #!/bin/bash SWAP="${1:-512}" NEW="$[SWAP*1024]"; TEMP="${NEW//?/ }"; OLD="${TEMP:1}0" sed "/^Swap\(Total\|Free\):/s,$OLD,$NEW," /proc/meminfo &...
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139 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 (/usr/src/...
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83 views

There is no /proc/bus/usb directory

I'm running a centos VM on ESXi. Does the /proc/bus/usb directory not show up until a USB device is connected? I just added a USB controller to the VM (it previously had non) and ran lsusb: $ ...
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proc system interrupts information

There are many info under /proc For examples, for each process : raw format : cat /proc/< pid >/stat human readable : cat /proc/< pid >/status My goal is to read the info ...
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43 views

code generating /proc file system

In my assignment, I have added "casper" flag to task descriptor and it takes only 0, 1, 2 and 3 (default 0). I asked to "modify the code that generates the /proc filesystem so that its behavior is ...
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53 views

What does the “ss -s” result “Total:” value represent? How to get details on each of them?

I am trying to understand what the ss -s result line Total: value represents, along with how this number is related to the other numbers. Note, the following values are equivalent: ss -s Total: == ...
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Inconsistent output on /proc. Can some processes be hidden? [duplicate]

When I list /proc/<PID>, works as expected. But when I use ps or ls /proc | grep <PID>, the process is hidden. How & Why is this possible? [user@host ~]$ ls /proc/12263 attr ...
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What is kswapd_low_wmark_hit_quickly from /proc/vmstat

What does this parameter mean? # cat /proc/vmstat | grep low kswapd_low_wmark_hit_quickly 2
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359 views

How to know file name of sockets or pipes in /proc/[pid]/fd

In Android, #ls -l 15843/fd gives following output, lrwx------ u0_a179 u0_a179 2015-05-28 11:58 90 -> socket:[193728] lrwx------ u0_a179 u0_a179 2015-05-28 11:58 91 -> ...
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153 views

What are possible reasons why iwconfig is not updating connection stats?

I use iwconfig to show me some information about my current internet connection like this $ iwconfig wlp2s0 IEEE 802.11abg ESSID:"eduroam" Mode:Managed Frequency:2.462 GHz Access ...
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214 views

How can I get read/write instant speed of a Hard Drive using /proc/diskstats data?

I know that the proc/diskstats file presents these data columns: 1 - major number 2 - minor mumber 3 - device name 4 - reads completed successfully 5 - reads merged 6 - sectors read 7 - time spent ...
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Constant 60KB Shared library memory on /proc/<pid>/maps [duplicate]

In a quest for understanding RAM requirements of system processes, I arrived to analysis of /proc/pid/maps. I have noticed a pattern: many shared libraries have exactly 60KB space allocated in their ...