Bash 功能：在后台启动程序，确定PID和管道输出

Question

我想在 bash 中有一个函数，它在后台启动一个程序，确定该程序的 PID 并将其输出通过管道传输到 sed。我知道如何分别完成其中任何一个，但不知道如何一次完成所有这些。

我目前的情况是这样的：

# Start a program in the background
#
# Arguments:
#  1  - Variable in which to "write" the PID
#  2  - App to execute
#  3  - Arguments to app
#
function start_program_in_background() {

    RC=; shift

    # Start program in background and determine PID
    BIN=; shift
    ( $BIN $@ & echo $! >&3 ) 3>PID | stdbuf -o0 sed -e 's/a/b/' &
    # ALTERNATIVE $BIN $@ > >( sed .. ) &

    # Write PID to variable given as argument 1
    PID=$(<PID)
    # when using ALTERNATIVEPID=$!
    eval "$RC=$PID"

    echo "$BIN ---PID---> $PID"
}

我提取PID的方式受到了[1]的启发。评论中有第二种变体。当执行使用上述函数启动程序的脚本时，它们都显示后台进程的输出，但是当我管道

时没有输出

[1] How to get the PID of a process that is piped to another process in Bash?

有什么想法吗？

Answer 1

解法：

多亏了一些有用的评论，我自己想出了这个。为了能够标记为已解决，我在这里发布了工作解决方案。

# Start a program in the background
#
# Arguments:
#  1  - Variable in which to "write" the PID
#  2  - App to execute
#  3  - Arguments to app
#
function start_program_in_background() {

    RC=; shift

    # Create a temporary file to store the PID
    FPID=$(mktemp)

    # Start program in background and determine PID
    BIN=; shift
    APP=$(basename $BIN)
    ( stdbuf -o0 $BIN $@ 2>&1 & echo $! >&3 ) 3>$FPID | \
            stdbuf -i0 -o0 sed -e "s/^/$APP: /" |\
            stdbuf -i0 -o0 tee /tmp/log_${APP} &

    # Need to sleep a bit to make sure PID is available in file
    sleep 1

    # Write PID to variable given as argument 1
    PID=$(<$FPID)
    eval "$RC=$PID"

    rm $FPID # Remove temporary file holding PID
}

Bash 功能：在后台启动程序，确定PID和管道输出

Bash function: start program in background, determine PID and pipe output

bash

background

pid

pipe