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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195 views

Accounting for /proc/net/dev reported traffic

I noticed that according to /proc/net/dev I am constantly receiving around 6Kb/s on my wireless usb interface. But I can't account for anything even close to that with the individual connections that ...
13
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6answers
398 views

How do I source another process's environment variables?

If I examine /proc/1/environ I can see a null-byte-delimited string of process 1's environment variables. I'd like to bring these variables into my current environment. Is there an easy way to do ...
4
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1answer
39 views

Does pipe's link target exist somewhere in the filesystem?

I'm talking about this: $ readlink <(echo test) pipe:[80076194] Is pipe:[80076194] a path to the target or just indication that the file descriptor is connected to the pipe and doesn't exist in ...
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1answer
43 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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1answer
55 views

Kernel /proc ipv6 settings precedence

I'm about to connect our network to the IPv6 Internet and need to control the kernel ipv6 settings found under /proc. I know there are configurations for each interface, for all interfaces, and the ...
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2answers
45 views

Portability of file descriptor links

I've always wondered this but never took the time to find out, so I'll do so now - how portable is the usage shown here of either /proc/$$/fd/$N or /dev/fd/$N? I understand POSIX guarantees /dev/null, ...
2
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2answers
287 views

iotop but for particular disk?

Is there a tool like iotop but for monitoring IO on specific volumes? (Or perhaps I missed a way to filter iotop?) If not is there any way to get at this information via (say)/proc? (dstat etc. ...
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7answers
34k views

Tell fs to free space from deleted files NOW

Is there a way to tell the kernel to give back the free disk space now? Like a write to something in /proc/ ? Using Ubuntu 11.10 with ext4. This is probably an old and very repeated theme. After ...
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3answers
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What happens when I run the command cat /proc/cpuinfo?

What happens when I write cat /proc/cpuinfo. Is that a named pipe (or something else) to the OS which reads the CPU info on the fly and generate that text each time I call it?
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1answer
405 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 ...
3
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1answer
47 views

Whats the correct value to base the maximum number of CPU's to sched_setaffinity to?

I have some confusion as to whats the correct value to use for the number of CPU's I can use to make a CPU_SET for a sched_setaffinity call on my system. My /proc/cpuinfo file: processor : 0 ...
2
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1answer
475 views

/proc/cpuinfo showing zero cpu clock speed

I saw an interesting issue where the cpuinfo file from /proc filesystem shows the cpu clock speed as zero. It is a physical host with no virtualization. Can someone explain to me some probable reasons ...
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1answer
509 views

sysctl: /proc/sys/net/ipv[46]/conf/: what's the difference between “all”, “default” and “eth*”?

In sysctl, the /proc/sys/net/ipv[46]/conf/ keys have the following subkeys: all, default, and a key for each network interface. For example, on a machine with a single network interface eth0, it will ...
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2answers
75 views

How to get total disk read/write in bytes per hdd device from /proc

How to get total disk read/write in bytes per hdd device? for example if i have sda, sdb, and sdc, is there any file on /proc that i could use similar to /proc/net/dev for networking?
3
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1answer
89 views

Does “syslogd” cause “cat /proc/kmsg” not to work properly?

I'm using cat /proc/kmsg to determine which process and file was involved in certain disc writes. I'm using the method given in this answer. But when I use cat /proc/kmsg, the output doesn't always ...
3
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1answer
320 views

Is there an easy way to log all commands executed, including command line arguments?

I am trying to find how to log a specific instantiation of rrdtool to see whether the path it is receiving is incorrect. I know I could wrap the executable in a shell script that would log the ...
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0answers
42 views

/proc/self/maps - 3rd mapped piece of file?

I'm running Arch linux on my laptop, which is kernel 3.12.9 right now. Something has changed about the way the kernel maps in a dynamically-linked executable and I can't figure it out. Here's the ...
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1answer
62 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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3answers
73 views

How to find out easily whether a block device (or a part of it) is mounted somehow

I want to know what the easiest way is to determine (without root privilege) whether a block device (say sdb) or any part of it is mounted (and which part of it). Checking /proc/mounts for sdb is not ...
2
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1answer
57 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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2answers
87 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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1answer
194 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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2answers
1k views

“echo 3 > /proc/sys/vm/drop_caches” - Permission denied as root

I am currently having some issues with the cache. It is a little too much right now so I wanted to clear it. I googled and found this little command: sync && echo 3 > ...
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1answer
173 views

root permission denied on /proc/1/exe

I just performed a fresh ubuntu install and i am seeing the following in lsof: userA@az1:~$ lsof COMMAND PID TID USER FD TYPE DEVICE SIZE/OFF NODE NAME init 1 ...
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1answer
544 views

Explain EV in /proc/bus/input/devices data

Can anybody explain to me what the EV value in /proc/bus/input/devices is? The keyboard always has value 120013. Why?
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2answers
2k views

Arch linux : pacman does not work when chrooting

I have Ubuntu installed on my computer. I decided to install Arch linux, but I skipped the part about Grub installation as it is already installed. Seeing that Arch does not show up in Grub's menu ...
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2answers
313 views

Determine if a specific process is 32- or 64-Bit

Given a 2.6.x or newer Linux kernel and existing userland that is capable of running both ELF32 and ELF64 binaries (i.e. well past How do I know that my CPU supports 64bit operating systems under ...
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2answers
216 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
486 views

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 ...
2
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2answers
148 views

where does lspci gather its information from?

In kernel.org's documentation on proc I found "[The latest version of this document is available online". There I says: "… lspci is a synonym for cat /proc/pci". Which isn't the ...
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2answers
114 views

UUID in /etc/mtab

In some versions of Ubuntu. Disks are mounted by UUID. in My machine, /proc/mounts /dev/disk/by-uuid/UUID / ext4 rw,relatime,errors=remount-ro,barrier=1,data=ordered 0 0 /etc/fstab UUID=U-U-I-D ...
6
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1answer
420 views

How do I know if a serial port is actually transmitting data, without opening the device?

I have a high-availability cluster (Heartbeat) connected via serial line and two ethernet NICs. I'd like to set up a monitoring script capable of recognizing disconnected serial line (basically the ...
4
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1answer
59 views

Why is UID information not in /proc/X/stat?

This is a silly question for the sake of academics; I know where to get the UID information if I need it. According to the proc(5) man page: /proc/[number]/stat Status ...
3
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1answer
92 views

Is there a way to show all flags in /proc/mounts?

Some filesystem flags seem to be hidden in /proc/mounts, depending on whether they are defined as defaults. Is there a way to show all flags in /proc/mounts, also including the default ones? And if ...
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2answers
4k views

/proc/PID/fd/X link number

In Linux, in /proc/PID/fd/X, the links for file descriptors that are pipes or sockets have a number, like: l-wx------ 1 user user 64 Mar 24 00:05 1 -> pipe:[6839] l-wx------ 1 user user 64 Mar 24 ...
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0answers
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Value of /proc/sys/kernel/hostname

I've set computer hostname in /etc/hostname a while ago (also there are record in /etc/hosts). Everything worked fine, but recently I've noticed that value of hostname (and /proc/sys/kernel/hostname) ...
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2answers
224 views

Linux /proc/sys/kernel: where are the files sysrq-sticky, sysrq-key, and sysrq-timer?

Documentation for Red Hat Enterprise Linux 3 (section 5.3.9.3) mentions these files in /proc/sys/kernel/: sysrq sysrq-key sysrq-sticky sysrq-timer The documentation for RHEL 5 also mentions them. ...
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2answers
132 views

Which of proc, sys etc. should be bind-mounted (or not) when chrooting into a “replacement” distribution?

This answer to another question basically boils down to chrooting into another Linux distribution in order to mainly use that as a replacement to its too restricted (but irreplaceable) parent. The ...
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1answer
132 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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2answers
67 views

Detecting Kernal Thread on Older Kernel Version

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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3answers
170 views

Command line options of rackup are not shown in ps output or procfs

As you know if you wish to get command-line runtime arguments for running command you can parse ps -e or /proc/<pid>/cmdline. But I have encountered issue when this method returns only command ...
4
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1answer
521 views

Notify of changes on a file under /proc

I have written a small 'daemon' in bash that will switch to the headphones if they are detected, and if not, switch to an external USB speaker with PulseAudio. What I'm looking for is some way to get ...
3
votes
2answers
61 views

How proc gets updated about the devices [duplicate]

If i do cat /proc/asound/cards it lists all the sound card details from where proc gets this information.This file is continuously updating what if i want to make a manual entry
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2answers
377 views

/proc/sys vs /sys/modules/mod/parameter

I've been wondering for last few days how exactly does it work. We can set kernel runtimes parameters using sysctl or echo boolen 1> /proc/sys/module/exactParameter but in ...
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4answers
6k views

Find out what device /dev/root represents in Linux?

On linux, there is a /dev/root device node. This will be the same block device as another device node, like /dev/sdaX. How can I resolve /dev/root to the 'real' device node in this situation, so ...
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2answers
75 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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1answer
211 views

How to get the actual keyboard device given the output of /proc/bus/input/devices?

When I run: cat /proc/bus/input/devices ...I receive the following output: ... I: Bus=0003 Vendor=040b Product=2000 Version=0110 N: Name="Generic USB Keyboard" P: Phys=usb-0000:00:1d.0-1/input0 ...
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1answer
103 views

How are username, date and time are registered in kernel

How is the date and time of kernel compilation registered in kernel image? cat /proc/sys/kernel/version #35~precise1-Ubuntu SMP Fri Jan 25 17:15:33 UTC 2013
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2answers
128 views

Determining if a file system object is a procfs/sysfs/etc. “virtual file” which doesn't report its length correctly

Some kinds of pseudo-files, like many in the procfs and sysfs virtual file systems, have no file size (stat returns st_size == 0) and do not support SEEK_END in fseek. These file system objects, such ...
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2answers
293 views

mount options shown in /proc/mounts

IIRC then the mount options shown in /proc/mounts have changed. Some time ago acl and user_xattr were shown, now it seems that only noacl and nouser_xattr are shown if these features are turned off. ...