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conditional expression bash script

For example, conditional expression bash script
conditional expression bash script


File operators:
-a FILE        True if file exists.
-b FILE        True if file is block special.
-c FILE        True if file is character special.
-d FILE        True if file is a directory.
-e FILE        True if file exists.
-f FILE        True if file exists and is a regular file.
-g FILE        True if file is set-group-id.
-h FILE        True if file is a symbolic link.
-L FILE        True if file is a symbolic link.
-k FILE        True if file has its `sticky' bit set.
-p FILE        True if file is a named pipe.
-r FILE        True if file is readable by you.
-s FILE        True if file exists and is not empty.
-S FILE        True if file is a socket.
-t FD          True if FD is opened on a terminal.
-u FILE        True if the file is set-user-id.
-w FILE        True if the file is writable by you.
-x FILE        True if the file is executable by you.
-O FILE        True if the file is effectively owned by you.
-G FILE        True if the file is effectively owned by your group.
-N FILE        True if the file has been modified since it was last read.
FILE1 -nt FILE2  True if file1 is newer than file2 (according to modification date).
FILE1 -ot FILE2  True if file1 is older than file2.
FILE1 -ef FILE2  True if file1 is a hard link to file2.

String operators:
-z STRING: True if string is empty.
-n STRING: STRING True if string is not empty.
STRING1 = STRING2: True if the strings are equal.
STRING1 != STRING2: True if the strings are not equal.
STRING1 < STRING2: True if STRING1 sorts before STRING2 lexicographically.
STRING1 > STRING2: True if STRING1 sorts after STRING2 lexicographically.

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