running strace for specific period of time

Question

How to run strace on a user process for specific period of time, say 1 minute, without terminating the user process and without using Ctrl+C?

I want to create a script to automating strace execution for a user process.

Answer 1

With timeout in GNU coreutils, you can do:

• Get the process id
• Run timeout 60 strace -p PID

Here is an example.

test.sh:

#!/bin/bash

while :; do
    echo "$$"
    sleep 100
done

Run it:

$ ./test.sh
27121

Run strace with timeout:

% cuonglm at ~
% timeout 60 strace -p 27121
Process 27121 attached - interrupt to quit
wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 27311
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
--- SIGCHLD (Child exited) @ 0 (0) ---
wait4(-1, 0x7fff374b8598, WNOHANG, NULL) = -1 ECHILD (No child processes)
rt_sigreturn(0xffffffffffffffff)        = 0
rt_sigaction(SIGINT, {0x45c4d0, [], SA_RESTORER, 0x7fcdc10e05c0}, {0x443910, [], SA_RESTORER, 0x7fcdc10e05c0}, 8) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
write(1, "27121\n", 6)                  = 6
rt_sigprocmask(SIG_BLOCK, [INT CHLD], [], 8) = 0
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fcdc1a699d0) = 27328
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGINT, {0x443910, [], SA_RESTORER, 0x7fcdc10e05c0}, {0x45c4d0, [], SA_RESTORER, 0x7fcdc10e05c0}, 8) = 0
wait4(-1,

After 1 minute:

....
rt_sigprocmask(SIG_BLOCK, [INT CHLD], [], 8) = 0
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fcdc1a699d0) = 27328
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGINT, {0x443910, [], SA_RESTORER, 0x7fcdc10e05c0}, {0x45c4d0, [], SA_RESTORER, 0x7fcdc10e05c0}, 8) = 0
wait4(-1,  <unfinished ...>
Process 27121 detached
% cuonglm at ~

Answer 2

timeout seems to be the most general solution. Just type timeout 60s command and the command will end in 60 seconds. It will send a TERM if the program is running by default. You can specify the signal you want to get, using the --signal option.

The duration can be set in seconds, minutes, hours or days, each of them has an specific suffix to determine what will be used.