Various judgment grammars in the shell

Shell judgment

#按照文件类型进行判断

-B To determine if the file exists and whether it is a fast device file (The block device file is true)

-C Determines whether the file exists and whether it is a character device file (the character device file is true)

-D to determine if the file exists and is a directory file (the directory is true)

-E to determine if a file exists, exists as true

-F to determine if the file exists and is a normal file (exists as true)

-L to determine if the file exists and is a symbolic link file (the symbolic link file is True)

-P to determine if the file exists and is a pipe file (the pipe file is true)

-S to determine if the file exists and is empty (non-null is true)

-S to determine if the file exists and is a socket file (the socket file is true)

#按照文件权限进行判断

-R to determine if the document has Read permissions

-W to determine if Write permission is available

-X determines whether the executable

#两个文件之间的比较

Files 1-nt File 2 Determine if the modification time of file 1 is newer than file 2 (if new is true)

Files 1-ot File 2 Determine if the modification time of file 1 is older than file 2 (if old is true)

Files 1-ef file 2 Determine whether the file 1 is the same as the inode number of file 2, it can be understood that two files are the same file, this judgment is the best way to judge hard links

#两个整数之间的比较

-eq determine if two values are equal

-ne determine if two values are not equal

-gt Judging whether it is greater than

-lt Judging whether it is less than

-ge judgment is greater than or equal to

-le determine if it is less than or equal

#字符串之间的判断

-Z to determine if the string is empty

-N to determine if the string is non-null

String 1 = = 2 Determine if string 1 is equal to string 2

String 1! = 2 to determine if string 1 is not equal to string 2

#多重条件判断

Judge 1-a judgment 2 logic with, Judge 1 and Judge 2 are set up, the final result is true

Judge 1-o Judge 2 logic or, judging 1 and judging 2 has a set up, the result is true

！ The judgment logic does not make the original judgment be reversed

Note: This article only to oneself later study reference

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Various judgment grammars in the shell