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youni's questions

Martin Hope
youni
Asked: 2024-07-27 16:24:27 +0800 CST
  • 11

我希望保持系统清洁，并记录下已安装的软件包，以便以后可以删除它们。但有时依赖关系仍然存在。

我安装了该libasound2-plugin-equal包，它也拉进来了caps。我删除了libasound2-plugin-equal，但apt没有删除caps。

root@devuan:~# apt install libasound2-plugin-equal
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following additional packages will be installed:
  caps
The following NEW packages will be installed:
  caps libasound2-plugin-equal
0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 230 kB of archives.
After this operation, 632 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://deb.devuan.org/merged daedalus/main amd64 caps amd64 0.9.26-1 [215 kB]
Get:2 http://deb.devuan.org/merged daedalus/main amd64 libasound2-plugin-equal amd64 0.6-8 [14.9 kB]
Fetched 230 kB in 1s (211 kB/s)               
Selecting previously unselected package caps.
(Reading database ... 268554 files and directories currently installed.)
Preparing to unpack .../caps_0.9.26-1_amd64.deb ...
Unpacking caps (0.9.26-1) ...
Selecting previously unselected package libasound2-plugin-equal:amd64.
Preparing to unpack .../libasound2-plugin-equal_0.6-8_amd64.deb ...
Unpacking libasound2-plugin-equal:amd64 (0.6-8) ...
Setting up caps (0.9.26-1) ...
Setting up libasound2-plugin-equal:amd64 (0.6-8) ...
root@devuan:~# 
root@devuan:~# 
root@devuan:~# apt remove libasound2-plugin-equal
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following packages will be REMOVED:
  libasound2-plugin-equal
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 72.7 kB disk space will be freed.
Do you want to continue? [Y/n] y
(Reading database ... 268570 files and directories currently installed.)
Removing libasound2-plugin-equal:amd64 (0.6-8) ...
root@devuan:~# 
root@devuan:~# 
root@devuan:~# apt autoremove
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
root@devuan:~#

autoremove没有帮助。autoremove既然该caps包是作为依赖项安装的，为什么这里没有反应？

apt
Martin Hope
youni
Asked: 2024-07-25 00:52:55 +0800 CST
  • 5

我希望在后台进程中 ping 我的路由器。我还想将 ping 进程作为服务来控制：启动、状态、停止。因此，我创建了锁定文件并将 PID 存储在其中。但实际上 PID 正在发生变化，我无法终止进程。我将 PID 存储在变量 $$ 中，但它会发生变化，我不知道原因，可能是因为我运行了管道，也可能是我在后台运行进程？您能否告诉我，如何在 sh 脚本中获取 PID，我在后台运行管道的位置？

我的 sh 脚本 ping.sh 的代码：$ cat ping.sh

#!/bin/sh


option=$1

if [ "$option" = "start" ]; then
  if [ -f /tmp/ping.lock ]; then
    echo There is another ping process. Exit
    exit 1
  else
    touch /tmp/ping.lock
    (ping 192.168.1.1 | ts | tee -a >> ~/1) &
    echo $$ > /tmp/ping.lock ##here i store script pid
  fi

elif [ "$option" = "status" ]; then
  if [ -f /tmp/ping.lock ]; then
    echo ping is running. PID:
    cat /tmp/ping.lock
  else
    echo ping is not running
  fi

elif [ "$option" = "stop" ]; then
  if [ -f /tmp/ping.lock ]; then
    echo killing ping process
    kill $(cat /tmp/ping.lock)
    echo removing lock file
    rm /tmp/ping.lock
    echo ping stopped.
  else
    echo ping is not running.
  fi

else
  echo Usage: $0 [start, status, stop]
fi

实际上，该行echo $$ > /tmp/ping.lock ##here i store script pid并不存储实际的 PID，但存储的 PID 消失了。并且此调用不会终止我的脚本：

$ ./ping.sh 
Usage: ./ping.sh [start, status, stop]
$ ./ping.sh start
There is another ping process. Exit
$ rm /tmp/ping.lock 
$ 
$ ./ping.sh start
$ ps -ef | grep ping
y         5271  2221  1 19:36 ?        00:00:10 /usr/lib/chromium/chromium --show-component-extension-options --enable-gpu-rasterization --no-default-browser-check --disable-pings --media-router=0 --enable-remote-extensions --load-extension
y         5993  4075  0 19:44 pts/2    00:00:00 vim ping.sh
y         6089     1  0 19:45 pts/5    00:00:00 /bin/sh ./ping.sh start
y         6090  6089  0 19:45 pts/5    00:00:00 ping 192.168.1.1
y         6095  5241  0 19:45 pts/5    00:00:00 grep ping
$ 
$ cat /tmp/ping.lock 
6087
$ 
$ ./ping.sh stop
killing ping process
./ping.sh: 27: kill: No such process

removing lock file
ping stopped.
$ 
$ ps -ef | grep ping
y         5271  2221  1 19:36 ?        00:00:10 /usr/lib/chromium/chromium --show-component-extension-options --enable-gpu-rasterization --no-default-browser-check --disable-pings --media-router=0 --enable-remote-extensions --load-extension
y         5993  4075  0 19:44 pts/2    00:00:00 vim ping.sh
y         6089     1  0 19:45 pts/5    00:00:00 /bin/sh ./ping.sh start
y         6090  6089  0 19:45 pts/5    00:00:00 ping 192.168.1.1
y         6148  5241  0 19:46 pts/5    00:00:00 grep ping

可以看到，调用后./ping.sh stop我的脚本进程仍然存在，其 PID 为 6089，而锁文件中存储的 PID 为 6087。如何获取锁文件中存储的 PID 6089？何时以及如何存储它？

bash