Linux脚本:如果[" $hostname " != " (none) "]比较不起作用

I'm getting hostname and ip address from server(ubuntu 12.04) as explained here. It works correctly. After a while, i realize that server returns "(none)" as hostname when it is offline. Now i'm trying to eliminate this error by comparing hostname with "(none)". I tried all of these(*) but none of them works:

我从服务器获得主机名和ip地址(ubuntu 12.04)。它工作正常。过了一会儿，我意识到服务器在脱机时返回“(none)”作为主机名。现在我试图通过比较主机名和“(none)”来消除这个错误。我尝试了所有这些(*)，但没有一个是有效的:

-- Getting hostname here    
hostname=$(grep "host-name" /var/lib/dhcp/dhclient.${interface}.leases | tail -n1 | cut -d"\"" -f2 | cut -d"." -f1)

-- Trying to compare it with "(none)"
    * if [ "$hostname" != "(none)" ] then ... else ... fi
    * if [[ $hostname != "(none)" ]] then ... else ... fi
    * nouser="(none)"  if [ "$hostname" != "$nouser" ] then ... else ... fi

What am i doing wrong ? Thx for any help.

我做错了什么?感谢任何帮助。

3 个解决方案

#1

You need a semicolon after ]

后面需要一个分号

if [ ... ]; then ...; else ...; fi

or newlines:

或换行:

if [ ... ]
then
   ...
else
   ...
fi

#2

This should work;

这应该工作;

hostname="(foo)"
if [ "$hostname" == "(foo)" ]; then echo "equals"; else echo "not equals"; fi

#3

Use $HOSTNAME - my reasoning, which can user to validate other $ variables:

使用$HOSTNAME -我的推理，它可以用户验证其他$ variable:

wilf@comp:~$ echo $hostname

wilf@comp:~$ echo $HOSTNAME
comp
wilf@comp:~$

@ wilf@comp:~$ echo $hostname wilf@comp:~$ echo $hostname comp comp wilf@comp:~$

For some reason, $hostname does not seem to work (Ubuntu 13.10, haven't tried this on other Linuxes)

由于某些原因，$hostname似乎不能工作(Ubuntu 13.10，没有在其他linux上尝试过)

#1