SIGTERM 不终止脚本

Question

我正在尝试理解这个脚本：

#!/usr/bin/env sh

trap "pkill -f sleep" term

sleep 1000

在运行脚本之后，我想通过发送 SIGTERM:

来停止它

# run script in the background
$ ./signals.sh &
[1] 5389

# check if script is running
$ ps aux | grep 'signals.sh\|sleep' | grep -v grep
sergioro  5389  0.0  0.0 216520  3112 pts/0    S    09:07   0:00 sh ./signals.sh
sergioro  5390  0.0  0.0 214984   708 pts/0    S    09:07   0:00 sleep 1000

# send SIGTERM to script
$ pkill -fe signals.sh
sh killed (pid 5389)

# why hasn't the script stopped after receiving SIGTERM?
$ ps aux | grep 'signals.sh\|sleep' | grep -v grep
sergioro  5389  0.0  0.0 216520  3112 pts/0    S    09:07   0:00 sh ./signals.sh
sergioro  5390  0.0  0.0 214984   708 pts/0    S    09:07   0:00 sleep 1000

# send SIGTERM to `sleep` command
$ pkill -fe sleep
sleep killed (pid 5390)
Terminated

# script has stopped
$ ps aux | grep 'signals.sh\|sleep' | grep -v grep

我的问题是如何通过将 SIGTERM 发送到脚本本身而不是 sleep 命令来停止脚本？为什么脚本中的 trap 没有终止睡眠命令？

Answer 1

只有在 sleep 完成后，shell 才能处理 trap。

这可以达到你的预期:

#!/usr/bin/env sh

trap "pkill -f sleep" term

sleep 1000 & wait

参见手册页的 SIGNALS 部分，尤其是最后一段：

If bash is waiting for a command to complete and receives a signal for which a trap has been set, the trap will not be executed until the command completes. When bash is waiting for an asynchronous command via the wait builtin, the reception of a signal for which a trap has been set will cause the wait builtin to return immediately with an exit status greater than 128, immediately after which the trap is executed.

SIGTERM 不终止脚本

SIGTERM does not terminate script

sh