Questions tagged [strace]
The strace tag has no usage guidance.
43 questions
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How to save a debug trace of an application that hangs/crashes the OS/PC?
Rationale
For this AMD GPU driver bug of mine, I want to capture a (stack/back)trace of the Prism Launcher Flatpak package. [1] However, as the afore-referenced bug explains, the issue experienced ...
4
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1
answer
478
views
CURL fails with exit code 18 for SFTP with just few bytes remaining for file sizes less than120KB , but not when I add strace to sshd
There is weird issue with curl in Amazon Linux 2 server.
It fails with exit code 18 with just about ~1MB bytes to read. So to troubleshoot the issue, I have setup local SFTP server.
so my curl command ...
- 309
1
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0
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105
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trace all file opens of executable with command line on macos
(related to How to find all the files that a program opens/read/write? , but unfortunately the answers are obsolete. it seems that security and multicore concerns have been mucking around with the ...
- 170
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ping: Name or service not known
Problem
ping: service.sys-dev.company.com: Name or service not known
host, nslookup and dig works
# host service.sys-dev.company.com
traefik-proxy.ingresscontrollers.svc.cluster.local has address 10....
- 21
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232
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Why does strace change command behavior?
I'm trying to use PICpgm to program a Microchip connected via GPIO. I'm running Raspbian Buster on a Pi 4B. Running as root, this command returns with no error but it doesn't print anything useful. ...
- 1,295
1
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1
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3k
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Why does sudo fail with strace?
I can run this command without issue.
/tmp $ sudo echo "hello world"
hello world
However, this command fails:
/tmp $ strace -o /tmp/out.log sudo echo "hello world"
sudo: effective ...
- 111
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0
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318
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Debugging slow cygwin bash startup
Running:
strace bash -li
and grepping for CreateProcessW:
182 590565 [main] bash 512 frok::parent: CreateProcessW (C:\cygwin64\bin\bash.exe, C:\cygwin64\bin\bash.exe, 0, 0, 1, 0x420, 0, 0, ...
- 246
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0
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135
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Why accept4() is slow with Apache?
I am running a website on Apache2 and I noticed that the first bit is always slow to come.
I tried to diagnose the problem with strace and found that accept4() is slow on each request.
Below the ...
- 11
0
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0
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832
views
2 java processing hanging for about 2.8s
I have 2 processes running on a VMWare server on the same vm. Centos 6.x
I ran strace on both processes and saved the output
6970 14:04:09.643295 futex(0x7f47d8027754, FUTEX_WAKE_OP_PRIVATE, 1, 1, ...
7
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0
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What’s the command line equivalent of strace on Windows?
I need to | findstr SomePATH in order to search if a program access and close immediately a specific path. On Linux, I would use myprogram | strace 2>&1 | grep SomPATH.
But what’s the ...
- 1,964
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1
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4k
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How to properly unescape strace output
How do I unescape strings outputted by strace? I see some advices to use printf '%b' for that, but that doesn't work correctly for me in some cases. Consider echo -ne '\037\061':
$ strace -e write ...
- 135
1
vote
1
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415
views
Intercept environment variables read by a process
I have a process that’s reading some environment variables to set itself up, but I’m not sure which one. The programming language is foreign to me, so let’s supposed I don’t have the source.
Is there ...
- 117
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214
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Libreoffice is eating all cpu
On my debian box, LibreOffice (even while idle) is eating 100% of the CPU is runs on.
I used strace and those 4 lines are constantly displayed as in a loop (as such I can tell which one comes first):
...
- 101
3
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1
answer
2k
views
Is it possible to strace pinging a host?
I am doing this
$ strace -f ping -s 1 www.google.com
execve("/bin/ping", ["ping", "-s", "1", "www.google.com"],
[/* 80 vars */]) = 0
getuid() = 1001
setuid(1001) ...
- 427
5
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1
answer
3k
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What can trigger a SIGPWR signal that interrupts a 'sendmsg' system call?
On a RHEL 6 host, I have a Cassandra server listening for TCP connections on localhost. In parallel, I have a client application that sends it requests. The client (C# Mono) uses sendmsg to send the ...
3
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1
answer
1k
views
docker version hangs before server info
Introduction
I'm attempting to use the following version of docker on a Linux VM (uname -a returns Linux xen 4.1.17-yocto-standard #1 SMP PREEMPT Thu Jun 2 13:29:47 PDT 2016 x86_64 GNU/Linux), built ...
- 247
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0
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815
views
dnsmasq; log querying process
I'm running dnsmasq in development and found that something on my laptop is putting forward queries for randomly generated domain names. Hence I'd like to display the PID/lsof -p output of the process ...
- 181
6
votes
1
answer
4k
views
Why strace sudo command bombs when sudo command works?
my username is allowed to execute
sudo command
then why does this bomb
strace sudo command
with the error:
sudo: must be setuid root
- 799
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1
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412
views
make strace print EUID
I'm trying to debug a permission problem, but I'm having trouble finding out with which EUID the application is being executed at the moment of the error.
Is there a way to make strace print the ...
- 255
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0
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1k
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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 ...
0
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1
answer
164
views
Is it secure to send strace log to third-party person?
I have some specific software - a console to access remote equipment. At some time it's UI starts to slow down too much (not because lack of resources but because some bug in that program). Developer ...
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2
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1
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227
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why doesn't strace use test syscalls to find out their indices in the system call table?
I understand that strace command uses ptrace(PTRACE_PEEKUSER, child, __builtin_offsetof(struct user, regs.orig_eax)) to find the index of a system call the tracee child is trapped at. Then to ...
- 799
2
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1
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617
views
why doesn't strace work on gcc -c
>echo > foobar.c
>strace gcc -c foobar.c 2>&1 | grep foobar.o
>
(nothing) - foobar.o is being written obviously, but I don't see it on strace. Why?
- 63
0
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1
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236
views
strace reports incorrect relative path?
I am using strace to report open and chdir system calls, and a fragment of its output is:
6791 chdir("//etc") = 0
6791 open("etc/fstab", O_RDONLY) = 3
This doesn't make ...
- 63
1
vote
1
answer
541
views
strace to discover sudo password persistence location
strace/dtrace/ltrace ... useful for lots of things, from finding hidden access violations to network socket tracing, but maybe it can't see all.
I haven't been able to figure out using strace (it ...
- 308
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1
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84
views
dtruss SQL-Queries on Mac OSX
In our shop we have an inhomogenous environment and doing Java on different boxes - mostly Mac OSX, me on Linux and one Windows box.
When it comes to debugging JPQL-Queries and its SQL-outcome, there ...
- 146
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0
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41
views
Assistance remembering the name of a Linux “strace”-based tool for file paths mocking
Once surfing the Internet I’ve seen a home page for a Linux tool which claims it can employ Linux systrace interface to execute other programs with manipulated paths. Something like that:
$ this-...
- 173
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0
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129
views
Tool similar to `strace` but for CPU instructions
I am hoping to find something similar to strace which will yield the instructions used by the CPU. For example, I have a simple loop which calculates a sum and prints out every tenth iteration
float ...
- 1,526
2
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1
answer
1k
views
ntfs disk dying or..? rsync and mkdir failing, strange behavior
System
root@host:~# uname -a
Linux host 3.2.0-4-686-pae #1 SMP Debian 3.2.57-3+deb7u1 i686 GNU/Linux
Mounts
root@host:~# mount | tail -2
/dev/sda1 on /mnt/sda1 type ntfs (rw,relatime,uid=1000,gid=...
- 134
2
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1
answer
2k
views
how to collect all files, that are opened by linux application
I want to collect a list of all files, that are opened by an application (in my case, it's a s/w bulder).
'strace -f' fails, because it mixes continuos opening from different forks, for example:
...
- 21
1
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1
answer
770
views
Tracing syscalls
I am trying to learn some tricks using "trace" (or dtrace or strace or truss), so I using the command:
trace -d [random PID]
I am getting the following error messages:
trace error: trace facility ...
- 387
4
votes
0
answers
957
views
Understanding the strace output on a mac [closed]
I am seeing syscalls that I do not understand. Multiple calls ending with _nocancel. E.g. open_nocancel, close_nocancel. What are these calls and where do I find information about these? Google does ...
- 161
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1
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2k
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Correlating strace output to source code function calls
I'm trying to fix a keyboard problem in a Linux application which I have the source code for. The application starts a TCP server and sends local keyboard and mouse events to connected clients. What's ...
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1
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2k
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What is a SIG_0 when looking at an strace
Attaching strace to a process that is using a lot of cpu, shows that the pid is 'killed' over and over.
The process is using 130% cpu. What is a tgkill( SIG_0) ?
strace -p 3876
nanosleep({0, ...
- 10.1k
6
votes
3
answers
6k
views
Interfacing strace with Process Name instead of PID
How do I implement a wrapper script pstrace in bash that changes the interface of
[sudo] strace -c -p [PID]
to
[sudo] pstrace -c -p [PROCESS-NAME]
similar to how
killall [PROCESS-NAME]
is used. ...
- 217
2
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1
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1k
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How to calculate and group the time differences of specified syscalls when running strace
I'm planing to do some web performance testing (to see how much time it's spent for each file), but it could be useful for any application.
I exactly know existence and how to use different ...
- 26.2k
4
votes
2
answers
3k
views
How do I strace the whole system?
strace allows you to monitor the activity of a particular program. How can I monitor the activity of all programs (expect for sshd/bash/strace_itself)?
Currently I'm using a hack like this:
function ...
- 17.5k
7
votes
2
answers
21k
views
Debugging connection timeouts using strace?
I'm trying to figure out why is Eclipse spinning, so I decided to fire up strace.
I found the eclipse process using:
$ ps ax | grep java
5546 ? Sl 19:04 /usr/bin/java ... [arguments ...
- 1,497
8
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6
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5k
views
Linux equivalent to Mac OS X's fs_usage
Is there a Linux equivalent to the Mac OS X command fs_usage? According to the man page it does the following: "report system calls and page faults related to filesystem activity in real-time".
I ...
- 156
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2
answers
3k
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How does 'strace' work?
Recently, I was using mv to move a large amount of files from my hard drive to a flash drive. I forgot to add a verbose flag so I had no idea "where" the move was at and how many transfers remained.
...
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1
vote
1
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7k
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Strange strace and setuid behaviour: permission denied under strace, but not running normally
This is related to this question.
I have a script (fix-permissions.sh) that fixes some file permissions:
#! /bin/bash
sudo chown -R person:group /path/
sudo chmod -R g+rw /path/
And a small c ...
- 290
4
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1
answer
2k
views
Why do strace/truss sometimes 'fix' stuck processes?
Sometimes you have a stuck process that's been stuck for a while, and as soon as you go to poke at it with strace/truss just to see what's going on, it gets magically unstuck and continues to run! So ...
- 351
13
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1
answer
7k
views
Will strace watch system calls recursively on child processes of the main process being observed?
If I run strace on a program and that program spawns a subprocess (e.g. perl's system() call), will strace report the system calls for the child process as well?
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