bash后台进程修改全局变量 [英] bash background process modify global variable
问题描述
我有一个全局的 var foo="some value" 和一个后台进程 back_func，我想让后台进程访问 $foo 并修改它的值，这可以被主进程看到.它类似于以下内容:
#!/bin/bash富=0功能 back_func {foo=$(($foo+1))回声返回$ foo"}(back_func) &回声全球$ foo"上面脚本的结果是
全局 0返回 1如何得到global和back都是'1'的结果?即后台进程的修改可以返回到主进程.
升级2019
使用 bash_ipc_demo 添加完成和图形生成器.
会合
如果你想有两个可以通信的独立进程，你必须在两个进程都可以到达的地方放置一个 rendez-vous.
这可能是一个简单的文件、fifo 管道、unix 套接字、TCP 套接字或其他(Rexx 端口).
bash 和其他 shell
Bash 没有与 rexx 端口等效的端口，因此有一个使用会合文件的小示例(在我的 Linux 上).
我正在使用共享内存 /dev/shm，以减少磁盘负载.
简单的计数器示例
$ back_func() {而:;做echo $(($(/dev/shm/foo;睡觉 .3;完毕;}让我们玩
$ echo 1 >/dev/shm/foo$ back_func &$ 回声 $(比现在停止:
$ fgback_func^C或
$ kill $!$[1]+ 终止的 back_func多个变量
对于有很多变量，可以通过一种很好的方式:
$ back_func() {声明 -A MYGLOBAL本地变量尽管 :;做((MYGLOBAL["counter"]++))IFS=/读取 -a vars <<<<$(/dev/shm/foo睡觉 1完毕}然后
$ back_func &[1] 27429$ ./dev/shm/foo$ 回声 ${MYGLOBAL['counter']}5$ 回声 ${MYGLOBAL['lpid']}27432从那里开始，为什么不呢:
$dumpMyGlobal() {./dev/shm/fooprintf "%8s " ${!MYGLOBAL[@]}回声printf "%8s " ${MYGLOBAL[@]}回声}$dumpMyGloball15m 正常运行时间 crt procs lpid active rand idle l05m柜台 l01m0.42 13815568.06 95 554 649 1 31135 21437004.950.38 73 0.50$dumpMyGloball15m 正常运行时间 crt procs lpid active rand idle l05m柜台 l01m0.41 13815593.29 120 553 727 2 3849 21437046.410.35 98 0.33或
$dumpMyGlobal() {./dev/shm/foo排序 <(粘贴 <(printf "%-12s
" ${!MYGLOBAL[@]}) <(printf "%s
" ${MYGLOBAL[@]}))}$dumpMyGlobal活跃 1柜台 297337闲置21435798.86l01m 0.40l05m 0.44l15m 0.45脂30418过程 553兰特 7328正常运行时间 13814820.80通过快照获取变量
最后是 getMyGlobalVar 函数
$ declare -A MYGLOBALLOCK # 快照变量$getMyGlobalVar () {本地同步=假[$1"==--同步"] &&班次&&同步=真如果 [ -z "${MYGLOBALLOCK[*]}" ] ||$同步；然后./dev/shm/foo对于我在 ${!MYGLOBAL[@]}做MYGLOBALLOCK[$i]=${MYGLOBAL[$i]}完毕菲回声 ${MYGLOBALLOCK[$1]}}将需要 --sync 标志来重新读取 rendez-vous 以便让您从同一个快照中查看每个字段.
$ getMyGlobalVar --sync idle362084.12$ getMyGlobalVar 空闲362084.12$ getMyGlobalVar 兰特1533$ getMyGlobalVar 兰特1533$ getMyGlobalVar --sync rand43256$ getMyGlobalVar 空闲362127.63完整可用的演示:
有一个完整的示例:
(注意: 命令最初被命名为 lastMinuteGraph，因为它的第一个版本只存储了 60 个值，现在这个使用 uptime_graph_val 用于存储值的数量.由于我使用了 -g 3600 参数，因此此命令可以命名为 lastHourGraph).
那么:
back_func 停止back_func 获取 backFunc_end2019-01-02 16:35:00I have a global var foo="some value" and a background process back_func, I want to the background process to access $foo and modify its value, which can be seen by the main process. It's something like the following:
#!/bin/bash
foo=0
function back_func {
foo=$(($foo+1))
echo "back $foo"
}
(back_func) &
echo "global $foo"
The result of the above script is
global 0
back 1
How could I get the result of global and back are both '1'?, i.e. the back ground process's modification can return back to the main process.
Upgrade 2019
Playing with bash_ipc_demo adding completion and a graph generator.
Rendez-vous
If you wanna have two independant process which could communicate, you have to place a rendez-vous somewhere both process can reach.
This could be a simple file, a fifo pipe, a unix socket, a TCP socket or maybe else (Rexx port).
bash and other shell
Bash don't have a equivalent to rexx port, so there is a little sample, using a rendez-vous file, that work (on my Linux).
I'm using shared memory /dev/shm, to reduce disk load.
Simple counter sample
$ back_func() {
while :;do
echo $(($(</dev/shm/foo)+1)) >/dev/shm/foo;
sleep .3;
done;
}
Let play
$ echo 1 >/dev/shm/foo
$ back_func &
$ echo $(</dev/shm/foo)
4
$ echo $(</dev/shm/foo)
21
Than stop now:
$ fg
back_func
^C
or
$ kill $!
$
[1]+ Terminated back_func
More than one variables
For having many vars, there could by a nice manner:
$ back_func() {
declare -A MYGLOBAL
local vars
while :; do
((MYGLOBAL["counter"]++))
IFS= / read -a vars <<< "$(</proc/uptime) $(</proc/loadavg)"
MYGLOBAL["uptime"]=$vars
MYGLOBAL["idle"]=${vars[1]}
MYGLOBAL["l01m"]=${vars[2]}
MYGLOBAL["l05m"]=${vars[3]}
MYGLOBAL["l15m"]=${vars[4]}
MYGLOBAL["active"]=${vars[5]}
MYGLOBAL["procs"]=${vars[6]}
MYGLOBAL["lpid"]=${vars[7]}
MYGLOBAL["rand"]=$RANDOM
MYGLOBAL["crt"]=$SECONDS
declare -p MYGLOBAL > /dev/shm/foo
sleep 1
done
}
Then
$ back_func &
[1] 27429
$ . /dev/shm/foo
$ echo ${MYGLOBAL['counter']}
5
$ echo ${MYGLOBAL['lpid']}
27432
and from there, why not:
$ dumpMyGlobal() {
. /dev/shm/foo
printf "%8s " ${!MYGLOBAL[@]}
echo
printf "%8s " ${MYGLOBAL[@]}
echo
}
$ dumpMyGlobal
l15m uptime crt procs lpid active rand idle l05m
counter l01m
0.42 13815568.06 95 554 649 1 31135 21437004.95
0.38 73 0.50
$ dumpMyGlobal
l15m uptime crt procs lpid active rand idle l05m
counter l01m
0.41 13815593.29 120 553 727 2 3849 21437046.41
0.35 98 0.33
or
$ dumpMyGlobal() {
. /dev/shm/foo
sort <(
paste <(
printf "%-12s
" ${!MYGLOBAL[@]}
) <(printf "%s
" ${MYGLOBAL[@]})
)
}
$ dumpMyGlobal
active 1
counter 297
crt 337
idle 21435798.86
l01m 0.40
l05m 0.44
l15m 0.45
lpid 30418
procs 553
rand 7328
uptime 13814820.80
Get variable with snapshot
and finally getMyGlobalVar function
$ declare -A MYGLOBALLOCK # snapshot variable
$ getMyGlobalVar () {
local i sync=false
[ "$1" == "--sync" ] && shift && sync=true
if [ -z "${MYGLOBALLOCK[*]}" ] || $sync; then
. /dev/shm/foo
for i in ${!MYGLOBAL[@]}
do
MYGLOBALLOCK[$i]=${MYGLOBAL[$i]}
done
fi
echo ${MYGLOBALLOCK[$1]}
}
will require --sync flag for re-reading rendez-vous in order to let you look about each fields from the same snapshot.
$ getMyGlobalVar --sync idle
362084.12
$ getMyGlobalVar idle
362084.12
$ getMyGlobalVar rand
1533
$ getMyGlobalVar rand
1533
$ getMyGlobalVar --sync rand
43256
$ getMyGlobalVar idle
362127.63
Full useable demo:
There is a full sample: bash_ipc_demo or bash_ipc_demo.shz
You could use by:
wget http://f-hauri.ch/vrac/bash_ipc_demo
source bash_ipc_demo
back_func help
Usage: back_func [-q] [start [-g N]|stop|restart|status|get|dump|help]
-q Quiet
-g N Start daemon, setting uptime_useGraph to N values
back_func status
Background loop function is not running.
back_func start -g 3600
back_func status
Background loop function (19939) is running.
From there, if you source bash_ipc_demo in another terminal, you could do the list into them.
You could even close the first terminal.
back_func dump
backFunc_count 13
backFunc_now 2016-04-06 17:03:19
backFunc_pid 19939
backFunc_running yes
backFunc_start 2016-04-06 17:03:07
cpu_numcores 2
loadavg_15min 0.44
loadavg_1min 0.66
loadavg_5min 0.54
loadavg_active 1
loadavg_last_pid 20005
loadavg_process 650
random 3714432
uptime_graph_val 3600
uptime_idle 425499.43
uptime_up 495423.53
uptime_usage1sec 9.90
uptime_usage 57.06
uptime_useGraph 57.06 8.91 7.50 6.93 12.00 9.41 7.84 9.90 7.50 11.88 7.92 9.31
9.90
Then, you could get one value
back_func get backFunc_pid newVar
echo $newVar
19939
or build a quick cpu graph:
lastMinuteGraph -p -o /tmp/lastMinuteGraph.png -W 640 -H 220
This will render a 640x220 PNG graphic, with uptime_graph_val values.
In this case, as back_func start was invoked with -g 3600 from more
than one hour, graphic show 3600 peek on 640 columns and 0-100% on 220 lines:
(Nota: Command was originaly named lastMinuteGraph as 1st version of this just stored 60 values, now this use uptime_graph_val for number of values to store. As I've used -g 3600 argument, this command could by named lastHourGraph).
Then:
back_func stop
back_func get backFunc_end
2019-01-02 16:35:00
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