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Shell 脚本 (bash/ksh)：读取变量需要 20 秒

发布于 2024-09-24 10:54:03 字数 250 浏览 7 评论 0原文

我需要等待输入 20 秒，之后 myscript 应该继续执行。
我尝试过使用 read -t20 var 但这仅适用于 bash。我在 Solaris 10 上使用 ksh。

有人可以帮助我吗？

编辑：20秒只是一个例子。假设需要等待 1 小时。但是这个人可以或不能在PC前面写输入，他不需要等待1个小时来输入输入，但是如果他不在PC前面那么shell应该在等待后继续执行一段时间了。

谢谢！

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瑶笙 2024-10-01 10:54:03

来自 man ksh：

TMOUT
如果设置为大于零的值，则如果在发出 PS1 提示符后规定的秒数内未输入命令，shell 将终止。可以使用该值的最大界限来编译 shell，该值不能超过。

我不确定这是否适用于 Solaris 上 ksh 中的 read。它确实适用于 ksh93，但该版本也有 read -t。

此脚本包括以下方法：

# Start the (potentially blocking) read process in the background

    (read -p && print "$REPLY" > "$Tmp") &  readpid=$!

    # Now start a "watchdog" process that will kill the reader after
    # some time:

    (
        sleep 2; kill $readpid >/dev/null 2>&1 ||
        { sleep 1; kill -1 $readpid >/dev/null 2>&1; } ||
        { sleep 1; kill -9 $readpid; }
    ) &     watchdogpid=$!

    # Now wait for the reading process to terminate. It will terminate
    # reliably, either because the read terminated, or because the
    # "watchdog" process made it terminate.

    wait $readpid

    # Now stop the watchdog:

    kill -9 $watchdogpid >/dev/null 2>&1

    REPLY=TERMINATED            # Assume the worst
    [[ -s $Tmp ]] && read < "$Tmp"

From man ksh:

TMOUT
If set to a value greater than zero, the shell terminates if a command is not entered within the prescribed number of seconds after issuing the PS1 prompt. The shell can be compiled with a maximum bound for this value which cannot be exceeded.

I'm not sure whether this works with read in ksh on Solaris. It does work with ksh93, but that version also has read -t.

This script includes this approach:

# Start the (potentially blocking) read process in the background

    (read -p && print "$REPLY" > "$Tmp") &  readpid=$!

    # Now start a "watchdog" process that will kill the reader after
    # some time:

    (
        sleep 2; kill $readpid >/dev/null 2>&1 ||
        { sleep 1; kill -1 $readpid >/dev/null 2>&1; } ||
        { sleep 1; kill -9 $readpid; }
    ) &     watchdogpid=$!

    # Now wait for the reading process to terminate. It will terminate
    # reliably, either because the read terminated, or because the
    # "watchdog" process made it terminate.

    wait $readpid

    # Now stop the watchdog:

    kill -9 $watchdogpid >/dev/null 2>&1

    REPLY=TERMINATED            # Assume the worst
    [[ -s $Tmp ]] && read < "$Tmp"

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