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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How do I find out what filesystem drivers are compiled-in into the linux kernel?

On a running linux system, what is a portable (among linux distributions) way to find out what filesystems the current kernel has compiled-in (not through modules) support for? Consider for example ...
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482 views

What is the Inverse of Idle in /proc/stat?

/proc/stat/ includes the following fields: "user", "nice", "system", "idle", "iowait", "irq", "softirq", "guest", "guest_nice", Which subset of those fields + idle accounts for 100% CPU? Is there ...
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1k views

When do jiffies increment? How a process runs in a jiffy?

I know that jiffies length is selected at kernel compile time and it is defaulted to 250 (4ms). Source: man 7 time - The Software Clock, HZ, and Jiffies I wonder what happens inside a jiffy. What are ...
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561 views

Plotting the sleep/wait chain of a process

I often want to know why a process in the middle of a pipeline is sleeping and not busy processing data. My current method is: find the pid of interest sudo strace -pt pid to get the blocking ...
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How can I test whether a block device is read-only from /sys or /proc?

On a CentOS6 system I have /dev/block/sr0 (read only) and /dev/block/sda (read/write). How can I find out programmatically which devices are read-only? There is a ro file in there, but it's '0' for ...
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Timer interrupts count in `/proc/interrupts` is updated very slowly and is very small

There is the result of cat /proc/interrupts|grep timer on my Ubuntu 11.04 machine: 0: 63 0 0 0 IO-APIC-edge timer LOC: 59 44 27 ...
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59 views

Why does each process folder under /proc contain the same information?

Under /proc/<PID>/net pseudo-file system each process seems to have files with the same content. For example I use cat /proc/<PID>/net/ip_tables_names to list iptables tables under the ...
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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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520 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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214 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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286 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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736 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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680 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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565 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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670 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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840 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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Can I add to /proc/self?

I want to create a number of named memory regions in my program, and mmap them somewhere so that other processes can read them. I can't guarantee that only one instance of my program will run at a ...
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184 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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316 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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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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Linux Unix /proc Rename

How can I rename /proc to something else forcefully? mv /proc /0 gives mv: cannot move ‘/proc’ to ‘/0’: Device or resource busy
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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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533 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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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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30 views

why do I find (under /proc/pid//fd) sockets with broken symlinks

I don't think they're closed, because I would expect that after a close() the fd would disappear, but I see a bunch of lingering fd -> socket[xxxxx] entries with broken symlinks which don't seem to be ...
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71 views

How to find out the reason why ssh processes are hanging?

When I run command like iostat -dkx 2 2 via ssh, I get the expected result, but the processes on the local computer are saying alive in status "interruptible sleep". Why is this happening? Is there a ...
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43 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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105 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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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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Can I set my core file location without being root?

It seems strange that I need to be root in order to say "place cores in my current directory" (via cat whatever /proc/sys/kernel/core_pattern). Isn't there any user-specific override for this?
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186 views

How does the proc/diskstats work to present that values? And for proc/stat and meminfo?

I am trying to get the diskstats data by same way that the file does. Is there any way to reach that values without reading that file? How the values are placed there? Is there any ".c" file that ...
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459 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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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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696 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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OOM Killer: Processes have a score of over a 1000

All top links when Googling for OOM score seem to indicate that the values must be between -1000 and 1000. I tried to verify that with a simple cat /proc/*/oom_score | sort -n | less and I ...
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241 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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294 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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35 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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342 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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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
357 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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“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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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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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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453 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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509 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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793 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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136 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 ...