Shell Test condition judgment

Test condition judgment

# symbol [] equals test command

Ten 5        # Judging the size of echo $?              # View the previous sentence The test command  returns the status "hello"     # To determine if the string length is 0[$  0"success" | | Exit # To determine the success hint, fail to exit

Expression is a string operation

-N STR   # string str is not empty-Z str   # string str is empty

　Expression for file operation

-A     # and, two conditions are true-B     # whether the block file     -P # file is a named pipe-C     # Whether the character file-   r     # file is readable-D     # whether a directory   -S     # Whether the length of the file is not zero-e     # The file exists if-   s # is     a socket file-F # whether the     normal file-   x # file is executable or     true-G     # Whether to set the file's SGID bit-u     # If the file's SUID bit-G     # File exists and is owned by the group All-W     # file is writable, then true-K     # file is set paste bit-  t fd
   
    # FD is an open file descriptor that is connected to the terminal (FD defaults to 1)-O     # or, a condition is true-o     # file exists and is owned by the user!      # Take the reverse
   

　Expression is an integer operation

Expr1-a EXPR2   # If the EXPR1 and EXPR2 evaluates to True, then true Expr1-o expr2   # True if EXPR1 or EXPR2 evaluates to True

　Two-value comparison

integer     string -lt      <         # less than -gt      >         # greater than -le      <=        # Less than or equal to-ge      >=        # is greater than or equal to-eq      = =        # equals -ne!      =        # does not equal

Shell Test condition judgment