I have a file which has environment variable listed like
我有一个文件，其中列出了环境变量
VAR_NAME=abc
and this file is sourced when needed. I want to add a new environment variable to the file if it's not present already. How do I search this file and replace/add a new value to it?
并在需要时提供此文件。我想在文件中添加新的环境变量（如果它尚未存在）。如何搜索此文件并替换/添加新值？
I was doing this till now:
我这样做到现在为止：
echo "string_created" >> fileName
this just appends a line and after few runs there were multiple lines with diff values. I can remove this file after one run of my program but that isn't definitive.
这只是附加一条线，经过几次运行后，有多条线具有diff值。我可以在一次运行程序后删除此文件，但这不是确定的。
1 个解决方案
#1
1
You can use grep:
你可以使用grep：
grep -q '^VAR_NAME=' file || echo 'VAR_NAME=abc' >> file
echo will execute when grep returns non-success return code.
当grep返回非成功返回码时，echo将执行。
#1
1
You can use grep:
你可以使用grep：
grep -q '^VAR_NAME=' file || echo 'VAR_NAME=abc' >> file
echo will execute when grep returns non-success return code.
当grep返回非成功返回码时，echo将执行。