“ file1.txt”包含以下几行：
environment=sit
javahome=/var/tmp/java
tcinstnace=/opt/apps
passowrd=asdf12
“ file2.txt”包含：
environment=qa
tcinstnace=/opt/apps
certpath=/opt/apps
javahome=/opt/apps
我想比较两个文件并打印两个文件之间的差异，例如（忽略匹配的行）
file1 file2
environment=sit` environment=qa
javahome=/var/tmp/java` javahome=/opt/apps`
passowrd=asdf12` missing
missing` certpath=/opt/apps