The proc tag has no wiki summary.
38
votes
3answers
16k views
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 ...
19
votes
2answers
573 views
How frequently is the proc file system updated on Linux?
How frequently is the proc file system updated on Linux? Is it 20 milliseconds (time quantum)?
13
votes
4answers
368 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 ...
13
votes
1answer
416 views
“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 ...
12
votes
2answers
267 views
When was a process started
To know when was a process started, my first guess was to check the time when /proc/<pid>/cmdline was written/modified the last time.
ps also shows a START field. I thought both of these ...
12
votes
4answers
2k views
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 ...
10
votes
2answers
430 views
Contents of /proc
Is there a site someplace that lists the contents of /proc and what each entry means?
10
votes
5answers
960 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 ...
8
votes
2answers
248 views
A hidden process, what it is?
[root@datacenteronline ~]# ssh root@192.168.1.172
Last login: Wed Apr 17 09:55:45 2013 from 192.168.1.187
[root@localhost ~]# ls /proc/ | grep 2266
[root@localhost ~]# cd /proc/2266
[root@localhost ...
7
votes
2answers
2k 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 ...
7
votes
4answers
301 views
Linking /proc/mnt to /proc/mounts
I understand that /proc filesystem reflects the output of various processes. Unfortunately, I have a propietary (romdump) binary that expects the mount table to appear as /proc/mtd, while my Android ...
6
votes
3answers
3k 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 ...
6
votes
2answers
259 views
Why do I have four CPUs listed in /proc/cpuinfo?
When I bought my Lenovo Thinkpad 520, it had Windows installed. I promptly cleaned that out and installed Fedora 16. I recently visited the /proc/cpuinfo and, much to my surprise, discovered that it ...
6
votes
1answer
851 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 ...
6
votes
1answer
231 views
Files bigger than max(off64_t) on Solaris, eg “/proc/../as”
How do I read or seek from a file that's bigger than the maximum off64_t? The problem arises because the address space of a process is represented in the /proc/.../as file, which is a huge sparse file ...
5
votes
1answer
464 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 ...
5
votes
3answers
523 views
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 ...
5
votes
3answers
1k views
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 ...
5
votes
3answers
889 views
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 ...
5
votes
2answers
202 views
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 ...
5
votes
1answer
165 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.
...
4
votes
1answer
890 views
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 ...
4
votes
1answer
693 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
votes
2answers
838 views
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 ...
3
votes
1answer
156 views
Timestamp of socket in /proc/<pid>/fd
If I list /proc/<pid>/fd I see a number of entries for sockets. These entries have timestamps. At first I thought they were when the socket was created. But it doesn't always appear to be the ...
3
votes
2answers
887 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
votes
1answer
376 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 ...
3
votes
1answer
360 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 ...
3
votes
1answer
170 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
votes
2answers
350 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 ...
3
votes
1answer
655 views
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 ...
3
votes
1answer
179 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 ...
2
votes
6answers
11k 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 ...
2
votes
2answers
191 views
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 ...
2
votes
1answer
350 views
Is there a utility that interprets /proc/interrupts data in time?
is there something out there ? Like top is for ps
2
votes
1answer
206 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 ...
2
votes
1answer
69 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?
2
votes
3answers
290 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
votes
1answer
1k 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/${pid}/task/.
But my ...
2
votes
2answers
64 views
files in /proc/$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 ...
2
votes
1answer
159 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, ...
2
votes
3answers
308 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 ...
2
votes
0answers
52 views
/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 ...
2
votes
1answer
80 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 ...
1
vote
2answers
350 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 ...
1
vote
2answers
158 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 ...
1
vote
2answers
61 views
Is it possible to tell df to use /proc/mounts instead of /etc/mtab?
Installing gentoo in chroot I found that commands like mount and df doesn't work: they try to read file /etc/mtab (which of course is empty).
Can I (for future use) setup or even recompile them so, ...
1
vote
2answers
417 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 ...
1
vote
1answer
75 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 ...
1
vote
1answer
32 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 ...
