Bash else/if捕获退出状态

请帮助我修复以下脚本中的“elseif”行，这样它就可以捕获zero的退出状态并无误地继续，因为我不知道构造此脚本的正确语法

我需要从下面的命令中捕获零，但是在脚本的括号内

softwareupdate -l 2>&1 | grep restart

我的剧本：

#!/bin/bash
PATH=/bin:/usr/bin:/sbin:/usr/sbin export PATH 
SWLOG=/var/log/swupdate.log

softwareupdate -l 2>&1 | grep "No new software available."

if [ $? -eq 0 ]

then
  echo "No new software was deemed to be available"

elif [ $(softwareupdate -l 2>&1 | grep restart & $? = 0) ]

then
  echo "RESTART will be needed"

else
  echo "Updates needed, but not restart"

fi

提前感谢您的建议和想法

---

Dan

您可以使用

grep-q

并避免使用

$？

：

#!/bin/bash
PATH=/bin:/usr/bin:/sbin:/usr/sbin export PATH 
SWLOG=/var/log/swupdate.log

if softwareupdate -l 2>&1 | grep -q "No new software available."
then
  echo "No new software was deemed to be available"    
elif softwareupdate -l 2>&1 | grep -q restart    
then
  echo "RESTART will be needed"    
else
  echo "Updates needed, but not restart"    
fi

---

您可以使用

grep-q

并避免使用

$？

：

#!/bin/bash
PATH=/bin:/usr/bin:/sbin:/usr/sbin export PATH 
SWLOG=/var/log/swupdate.log

if softwareupdate -l 2>&1 | grep -q "No new software available."
then
  echo "No new software was deemed to be available"    
elif softwareupdate -l 2>&1 | grep -q restart    
then
  echo "RESTART will be needed"    
else
  echo "Updates needed, but not restart"    
fi

---

如果软件更新-l 2>&1 | grep restart>/dev/null；然后

将完成这项工作。您不需要使用

$？

变量走人工弯路。

如果softwareupdate-l 2>&1 | grep restart>/dev/null；然后

将完成这项工作。您不需要使用

$？

变量进行人工迂回。

只需将输出发送到临时文件，而不是尝试对命令的输出求值两次

softwareupdate -l > temp.out 2>&1
grep "No new software available." temp.out > /dev/null
if [ $? -eq 0 ]
then
    echo "No new software was deemed to be available"
    exit
fi
grep "restart" temp.out > /dev/null
if [ $? -eq 0 ]
then
    echo "RESTART will be needed"
else
    echo "Updates needed, but not restart"
fi

---

不要尝试对命令的输出求值两次，只需将输出发送到临时文件即可

softwareupdate -l > temp.out 2>&1
grep "No new software available." temp.out > /dev/null
if [ $? -eq 0 ]
then
    echo "No new software was deemed to be available"
    exit
fi
grep "restart" temp.out > /dev/null
if [ $? -eq 0 ]
then
    echo "RESTART will be needed"
else
    echo "Updates needed, but not restart"
fi