Shell 实现多任务并发的示例代码

process_init # 创建进程
for city in ${cities[*]}
do
    cmd="handler $city"
    process_run $cmd 
done
process_wait # 等待进程

function _create_pipe()
{
    _PROCESS_PIPE_NAME=$(_get_uid)
    mkfifo ${_PROCESS_PIPE_NAME}
    eval exec "${_PROCESS_PIPE_ID}""<>${_PROCESS_PIPE_NAME}"
    for ((i=0; i < $_PROCESS_NUM; i++))
    do
        echo -ne "\n" 1>&${_PROCESS_PIPE_ID}
    done
}

exec fd <  file  #以读方式打开文件，并关联文件描述符fd
exec fd >  file  #以写方式打开文件，并关联文件描述符fd
exec fd <> file  #以读写方式打开文件，并关联文件描述符

# 测试
exec 8>file
echo "hello word!" 1>&8

file_fd=8
exec ${file_fd}>file

# 测试
bash test.sh
test.sh: line 7: exec: 8: not found

function process_run()
{
    cmd=$1
    if [ -z "$cmd" ]; then
        echo "please input command to run"
        _delete_pipe    
        exit 1
    fi
    _process_get
    {
        $cmd
        _process_post
    }&
}

chengsun@153_92:~/test> bash process_util.sh
chengsun@153_92:~/test> pstree -a
|`-sshd
|    |-bash
|    |   `-bash process_util.sh         #爷爷
|    |       |-bash process_util.sh     #爸爸
|    |       |   `-a.out                #儿子
|    |       |-bash process_util.sh        
|    |       |   `-a.out                   
|    |       `-bash process_util.sh
|    |           `-a.out

chengsun@153_92:~/test> ps -f -e -o pid,ppid,pgid,comm
 PID  PPID  PGID  COMMAND
24904 21976 24904 bash
19885 24904 19885  \_ bash            # 爷爷
19893 19885 19885      \_ bash        # 爸爸
19894 19893 19885      |   \_ a.out   # 儿子
19895 19885 19885      \_ bash
19896 19895 19885      |   \_ a.out
19897 19885 19885      \_ bash
19898 19897 19885          \_ a.out

function Print
{
    echo "Hello World!"
}
trap Print SIGKILL

void sig_handler(int signo)
{
    printf("sigterm signal\n");
}
int main()
{
    signal(SIGTERM, sig_handler);
    sleep(100);
    return 0;
}

chengsun@153_92:~/test> ./a.out &
[1] 19254
chengsun@153_92:~/test> kill 19254
sigterm signal

chengsun@153_92:~/test> man kill
0  All processes in the current process group are signaled.

function _clean_up
{
    # 清理管道文件
    _delete_pipe
    kill 0
    kill -9 $$
}
trap _clean_up SIGINT SIGHUP SIGTERM SIGKILL

# file: run.sh
#!/bin/sh
#load process library
source ./process_util.sh
function handler()
{
    city=$1
    ./main ${city}
}
process_init 23
for city in $cities
do
    cmd = "handler $city"
    process_run "$cmd"
done
process_wait