等到服務在 bash-script 中啟動

Question

我有一個 bash 腳本，它在后台啟動一些服務。 此服務成功啟動后，它會將“服務器處於活動狀態”打印到標准輸出。 我需要等到這個字符串出現，然后繼續執行我的腳本。 我怎樣才能做到這一點？

Answer 1

我會這樣做。

./server > /tmp/server-log.txt &
sleep 1
while ! grep -m1 'Server is active' < /tmp/server-log.txt; do
    sleep 1
done

echo Continue

這里-m1告訴grep(1)在第一場比賽時退出。

我用下面的玩具“服務”很好地回答了我的答案：

#! /bin/bash

trap "echo 'YOU killed me with SIGPIPE!' 1>&2 " SIGPIPE

rm -f /tmp/server-output.txt
for (( i=0; i<5; ++i )); do
    echo "i==$i"
    sleep 1;
done
echo "Server is active"
for (( ; i<10; ++i )); do
    echo "i==$i"
    sleep 1;
done
echo "Server is shutting down..." > /tmp/server-output.txt

如果你用echo Continue替換echo Continue; sleep 1; ls /tmp/server-msg.txt echo Continue; sleep 1; ls /tmp/server-msg.txt echo Continue; sleep 1; ls /tmp/server-msg.txt ，你會看到ls: cannot access /tmp/server-output.txt: No such file or directory證明“Continue”動作在Server is active的輸出Server is active后被觸發。

Answer 2

使用grep -q 。 -q選項使grep安靜，當文本出現時它會立即退出。

下面的命令在后台啟動./some-service ，並阻塞直到“服務器處於活動狀態”出現在標准輸出上。

(./some-service &) | grep -q "Server is active"

Answer 3

讓我閱讀service應用程序的服務狀態：

$ /sbin/service network status
network.service - Network Connectivity
   Loaded: loaded (/lib/systemd/system/network.service; enabled)
   Active: active (exited) since Ср 2014-01-29 22:00:06 MSK; 1 day 15h ago
  Process: 15491 ExecStart=/etc/rc.d/init.d/network start (code=exited, status=0/SUCCESS)

$ /sbin/service httpd status 
httpd.service - SYSV: Apache is a World Wide Web server.  It is used to serve HTML files and CGI.
   Loaded: loaded (/etc/rc.d/init.d/httpd)
   Active: activating (start) since Пт 2014-01-31 13:59:06 MSK; 930ms ago

它可以通過代碼完成：

function is_in_activation {
   activation=$(/sbin/service "$1" status | grep "Active: activation" )
   if [ -z "$activation" ]; then
      true;
   else
      false;
   fi

   return $?;
}

while is_in_activation network ; do true; done

Answer 4

您是否要求將 stderr 重定向到 stdout？

./yourscript.sh  2>&1 |grep "Server is active" && echo "continue executing my script"