关于signals

Linux下查看进程监听信号方法

最新推荐文章于 2024-12-25 11:30:04 发布

转载最新推荐文章于 2024-12-25 11:30:04 发布 · 383 阅读

文章标签：

#signals

RHEL7 同时被 2 个专栏收录

432 篇文章

订阅专栏

RHEL8

217 篇文章

订阅专栏

博客介绍了在Linux下查看进程监听信号的方法。可先找到进程的PID，查看相关文件，其中包含描述信号被阻塞、忽略或捕获的行。通过将十六进制的位掩码转换为二进制，能确定捕获的信号。还给出了相关参考链接。

https://unix.stackexchange.com/questions/85364/how-can-i-check-what-signals-a-process-is-listening-to

Under Linux, you can find the PID of your process, then look at /proc/$PID/status. It contains lines describing which signals are blocked (SigBlk), ignored (SigIgn), or caught (SigCgt).

# cat /proc/1/status
...
SigBlk: 0000000000000000
SigIgn: fffffffe57f0d8fc
SigCgt: 00000000280b2603
...

The number to the right is a bitmask. If you convert it from hex to binary, each 1-bit represents a caught signal, counting from right to left starting with 1. So by interpreting the SigCgt line, we can see that my init process is catching the following signals:

00000000280b2603 ==> 101000000010110010011000000011
                     | |       | ||  |  ||       |`->  1 = SIGHUP
                     | |       | ||  |  ||       `-->  2 = SIGINT
                     | |       | ||  |  |`----------> 10 = SIGUSR1
                     | |       | ||  |  `-----------> 11 = SIGSEGV
                     | |       | ||  `--------------> 14 = SIGALRM
                     | |       | |`-----------------> 17 = SIGCHLD
                     | |       | `------------------> 18 = SIGCONT
                     | |       `--------------------> 20 = SIGTSTP
                     | `----------------------------> 28 = SIGWINCH
                     `------------------------------> 30 = SIGPWR

(I found the number-to-name mapping by running kill -l from bash.)

另外：


Each process has a list (bitmask) of currently blocked signals. 
When a signal is blocked, it is not delivered (that is, no signal handling routine is called), but remains pending.

https://www.win.tue.nl/~aeb/linux/lk/lk-5.html