shell指令碼報錯："[: =: unary operator expected"

標籤：unary   operator   expected   

 shell指令碼報錯："[: =: unary operator expected" 

md5_109a="81ab961153b62d207f0f517048881b5d"
 md5_109b=`md5sum install.bin|awk ‘{print $1}‘`
 if [ $md5_109a != $md5_109b ]

原因，當檔案install.bin不存在時， $md5_109b為空白這樣對比字串就變成了

 if [ 81ab961153b62d207f0f517048881b5d ！=  ] 顯然語句就不合法了

可以改成

 if [[ $md5_109a != $md5_109b ]]

或者 if [ “$md5_109a ”a !=  “$md5_109b”a ]

問題解決

本文出自 “tonylinux” 部落格，請務必保留此出處http://tonylinux.blog.51cto.com/2268300/1441515

shell指令碼報錯："[: =: unary operator expected"