来自带有管道、引号等的命令的 Bash 变量
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Bash variable from command with pipes, quotes, etc
提问by TryTryAgain
I have a command I'm using to get the hostname.localdomain:
我有一个用于获取 hostname.localdomain 的命令：
dig axfr @dc1.localdomain.com localdomain.com | grep -i Lawler | awk '{ getline ; =substr(,1,length()-1); print ; exit }'
This nicely returns a result like:
这很好地返回了如下结果：
michael.lawler.localdomain.com
michael.lawler.localdomain.com
I'd like to further use that result as a variable in a Bash script.
我想进一步将该结果用作 Bash 脚本中的变量。
It seems I'm having trouble getting past the first pipe.
看来我在通过第一条管道时遇到了麻烦。
If I VAR="dig axfr @dc1.localdomain.com localdomain.com | grep -i Lawler | awk '{ getline ; $1=substr($1,1,length($1)-1); print $1 ; exit }'"
如果我 VAR="dig axfr @dc1.localdomain.com localdomain.com | grep -i Lawler | awk '{ getline ; $1=substr($1,1,length($1)-1); print $1 ; exit }'"
...I get back the entire zone transfer. I've also tried many minor changes, adding $before the digcommand, without quotes, but nothing seems to work. How can I fix this?
...我拿回了整个区域转移。我还尝试了许多小的更改，$在dig命令之前添加，没有引号，但似乎没有任何效果。我怎样才能解决这个问题？
回答by William Pursell
VAR=$( dig axfr @dc1.localdomain.com localdomain.com |
grep -i Lawler |
awk '{ getline ; =substr(,1,length()-1); print ; exit }' )
回答by bchurchill
Use backtics instead of quotes:
使用反引号代替引号：
VAR=`dig axfr @dc1.localdomain.com localdomain.com | grep -i Lawler | awk '{ getline ; =substr(,1,length()-1); print ; exit }'`
Backtics actually mean "run whatever is in here and return standard out as the expression's value", but quotes don't do that.
Backtics 实际上意味着“运行这里的任何内容并返回标准输出作为表达式的值”，但引号不会这样做。
