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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525 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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2answers
885 views

Chroot Risks w/ /dev and /proc

I am planning to set up a few chroot jails for some users to run/test Java applications (lets just assume each application is untrusted). Is there any risk involved with mounting /dev and /proc into ...
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2answers
8k views

File descriptor linked to socket or pipe in proc [duplicate]

Possible Duplicate: /proc/PID/fd/X link number i have a question regarding the file descriptors and their linkage in the proc file system. I've observed that if i list the file descriptors ...
3
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1answer
491 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 ...
3
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1answer
907 views

Do I have PCLMUL instruction set support?

Here are the flags from /proc/cpuinfo: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc ...
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2answers
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Is it possible to create a directory and file inside /proc/sys?

I am running CentOS 6.2 and I need to create a subdirectory named "crypto" inside /proc/sys. Inside /proc/sys/crypto, I need to create a file named test which contains the value "1". I have tried ...
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1answer
2k views

change environment of a running process

How might it be possible to alter some variable in the env of an already running process, for example through /proc/PID/environ? That "file" is read-only. Need to change or unset the DISPLAY variable ...
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2answers
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How is /proc/self implemented in Linux?

I was tinkering around with the /proc filesystem in Linux, and I came across /proc/self, which is a symbolic link to the process directory of the current process. I would like to know how it is ...
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7answers
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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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0answers
327 views

Process VSS and Size: entry in /proc/pid/smaps

I was wondering why the sum of all 'Size:' entries in /proc/pid/smaps does not equal the process VSS as reported by top, ps, /proc/pid/status VmSize, /proc/pid/statm 1st entry? Any clues?
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1answer
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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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3answers
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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 ...
8
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1answer
3k views

Is the sum of all PIDs “utime” the total system utime?

In order to measure a user's total CPU time, I'm using the "utime" field out of /proc/[pid]/stat: utime %lu Amount of time that this process has been scheduled in user mode, measured in ...
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1answer
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“ss” command in iproute package; why query slab table for timewait sockets?

Forgive me if this isn't the best forum for this question, but it seems more relevant to the kernel than to the programming itself. I'm writing a script that queries the system for open ports so that ...
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2answers
253 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
403 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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3answers
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Changing the UID of files in /proc

In a follow up to this question about changing the UID of a user, it is recommended to change the ownership of all files on the system (this answer) find / -uid 1000 -exec chown 5000 '{}' \+ where ...
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0answers
207 views

Rogue Java process brings my computer to a halt

In reference to my earlier post: Is there a log of past threads that are now closed? I gave the process a kill -STOP signal and started examining the details. I can't seem to figure out why it is ...
4
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1answer
2k views

What is the difference between /proc/self/stack and output from pstack?

I have been looking through the documentation for /proc and the "stack" object being a new'ish object in proc, I have also looked through the kernel commit to create it -- however the documentation ...
3
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2answers
2k views

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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1answer
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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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4answers
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How do I kill all a user's processes using their UID

I want to kill all running processes of a particular user from either a shell script or native code on a linux system. Do I have to read the /proc directory and look for these? Any ideas? Is there a ...
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4answers
10k 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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4answers
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How to check if /proc/ is mounted

How can I check if /proc/ is mounted? Using /etc/mtab is discouraged as it might be inconsistent. Using /proc/mounts is also not an option as might not exist if /proc/ is not mounted (although ...
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1answer
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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 ...
6
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1answer
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deleting a 'file' under /proc or /dev

I am using a cowdancer/debootstrap setup to generate a chroot. Of course, as I iterate, I generate some chroot configurations that are bad. I have found myself in an awkward situation where I have ...
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2answers
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/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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1answer
696 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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5answers
3k views

What happens when I open and read from /proc?

Does the hard drive need to be accessed or is everything done in memory? Basically I would like to constantly get updated values from meminfo and cpuinfo. Do I need to reopen the file and then reread ...
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2answers
700 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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4answers
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Read the stack of another process?

I'm trying to read a child process's stack but with no luck. I know it is possible using ptrace, but ptrace's interface allows you to read only one word at a time, and I'm trying to scan a larger ...
14
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4answers
506 views

How do I learn what I can do with /proc and /sys

I'd like to know more about the advanced uses of the /proc and /sys virtual filesystems, but I don't know where to begin. Can anyone suggest any good sources to learn from? Also, since I think sys has ...
82
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3answers
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How do I read from /proc/$pid/mem under Linux?

The Linux proc(5) man page tells me that /proc/$pid/mem “can be used to access the pages of a process's memory”. But a straightforward attempt to use it only gives me $ cat /proc/$$/mem ...
13
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3answers
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Contents of /proc

Is there a site someplace that lists the contents of /proc and what each entry means?