Linux (sed 初学者) 替换环境变量中的字符
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(sed beginner) replace characters in an env variable
提问by PapelPincel
How can I replace caracters "on the fly" when using sed ? Example :
使用 sed 时如何“即时”替换字符？例子 ：
I want this command to be executed : /bin/sed 's/HOSTNAME=.*/HOSTNAME=server_domain_com/g' /etc/sysconfig/network
我希望执行此命令： /bin/sed 's/HOSTNAME=.*/HOSTNAME= server_domain_com/g' /etc/sysconfig/network
Instead of this one : /bin/sed 's/HOSTNAME=.*/HOSTNAME=server.domain.com/g' /etc/sysconfig/network
而不是这个： /bin/sed 's/HOSTNAME=.*/HOSTNAME= server.domain.com/g' /etc/sysconfig/network
the string "server.domain.com" is contained in a env variable and I would like to replace the dots by an underscore before replacing the appropriate line in /etc/sysconfig/network.
字符串“server.domain.com”包含在环境变量中，我想在替换 /etc/sysconfig/network 中的相应行之前用下划线替换点。
Thank you!
谢谢！
采纳答案by lynxlynxlynx
You can do this with bash substitution too:
你也可以用 bash 替换来做到这一点：
/bin/sed -i "s/HOSTNAME=.*/HOSTNAME=${HOSTNAME//./_}/g" /etc/sysconfig/network
The //instructs it to change all occurences (like g in sed). Do not forget the -iflag to actually change the file, not just print it.
该//指示它改变所有出现（如克SED）。不要忘记-i实际更改文件的标志，而不仅仅是打印它。
回答by Igor Chubin
HOSTNAME=$(echo $HOSTNAME | sed s/from/to/g)
