获取后台进程的退出代码
我有一个从我的主bourne shell脚本调用的命令CMD，它永远需要花费很长时间。
我想修改脚本如下：
- 并行运行命令CMD作为后台进程(
CMD &). - In主脚本，每隔几秒就会有一个循环来监视衍生的命令。循环还向标准输出回显一些指示脚本进度的消息。当派生的命令terminates.
- Capture时，
- 退出循环，并报告派生的进程的退出代码。
有没有人能给我点建议来完成这个任务？
回答 12
Stack Overflow用户
发布于 2009-10-15 05:01:23
1:在bash中，$!保存最后执行的后台进程的PID。无论如何，这将告诉您要监视哪个进程。
4：wait <n>等待，直到PID为<n>的进程完成(它将阻塞，直到进程完成，所以您可能不想在确定进程完成之前调用它)，然后返回已完成进程的退出代码。
2、3：ps或ps | grep " $! "可以告诉你进程是否还在运行。这取决于你如何理解输出，并决定它离完成有多近。(ps | grep不是傻瓜式的。如果您有时间，您可以想出一种更健壮的方法来判断进程是否仍在运行)。
下面是一个框架脚本：
# simulate a long process that will have an identifiable exit code
(sleep 15 ; /bin/false) &
my_pid=$!
while ps | grep " $my_pid " # might also need | grep -v grep here
do
echo $my_pid is still in the ps output. Must still be running.
sleep 3
done
echo Oh, it looks like the process is done.
wait $my_pid
# The variable $? always holds the exit code of the last command to finish.
# Here it holds the exit code of $my_pid, since wait exits with that code.
my_status=$?
echo The exit status of the process was $my_statusStack Overflow用户
发布于 2015-04-09 17:53:23
当我有类似的需求时，我就是这样解决的：
# Some function that takes a long time to process
longprocess() {
# Sleep up to 14 seconds
sleep $((RANDOM % 15))
# Randomly exit with 0 or 1
exit $((RANDOM % 2))
}
pids=""
# Run five concurrent processes
for i in {1..5}; do
( longprocess ) &
# store PID of process
pids+=" $!"
done
# Wait for all processes to finish, will take max 14s
# as it waits in order of launch, not order of finishing
for p in $pids; do
if wait $p; then
echo "Process $p success"
else
echo "Process $p fail"
fi
doneStack Overflow用户
发布于 2017-09-14 15:07:01
背景子进程的pid存储在$!中。您可以将所有子进程的pids存储到一个数组中，例如PIDS[]。
wait [-n] [jobspec or pid …]等待每个进程ID pid或作业规范jobspec指定的子进程退出，并返回等待的最后一个命令的退出状态。如果给定了作业规范，则等待作业中的所有进程。如果没有给定参数，则等待所有当前活动子进程，并且返回状态为零。如果提供了-n选项，wait将等待任何作业终止并返回其退出状态。如果jobspec和pid都没有指定shell的活动子进程，则返回状态为127。
使用 wait 命令可以等待所有子进程完成，同时可以通过$?获取每个子进程的退出状态，并将状态保存到STATUS[]中。然后，您可以根据状态执行某些操作。
我已经尝试了以下两种解决方案，它们运行良好。solution01更简洁，而solution02则有点复杂。
solution01
#!/bin/bash
# start 3 child processes concurrently, and store each pid into array PIDS[].
process=(a.sh b.sh c.sh)
for app in ${process[@]}; do
./${app} &
PIDS+=($!)
done
# wait for all processes to finish, and store each process's exit code into array STATUS[].
for pid in ${PIDS[@]}; do
echo "pid=${pid}"
wait ${pid}
STATUS+=($?)
done
# after all processed finish, check their exit codes in STATUS[].
i=0
for st in ${STATUS[@]}; do
if [[ ${st} -ne 0 ]]; then
echo "$i failed"
else
echo "$i finish"
fi
((i+=1))
donesolution02
#!/bin/bash
# start 3 child processes concurrently, and store each pid into array PIDS[].
i=0
process=(a.sh b.sh c.sh)
for app in ${process[@]}; do
./${app} &
pid=$!
PIDS[$i]=${pid}
((i+=1))
done
# wait for all processes to finish, and store each process's exit code into array STATUS[].
i=0
for pid in ${PIDS[@]}; do
echo "pid=${pid}"
wait ${pid}
STATUS[$i]=$?
((i+=1))
done
# after all processed finish, check their exit codes in STATUS[].
i=0
for st in ${STATUS[@]}; do
if [[ ${st} -ne 0 ]]; then
echo "$i failed"
else
echo "$i finish"
fi
((i+=1))
donehttps://stackoverflow.com/questions/1570262
复制相似问题