Compare shell strings and determine whether the string is a number

This post was last edited by ps49324955 Integer comparison ------------------------------------------------------------ -EQ equals to, for example, if ["$ A"-EQ "$ B"] -Ne is not equal to, for example, if ["$ A"-ne "$ B"] -GT is greater than, for example, if ["$ A"-GT "$ B"] -Ge is greater than or equal to, for example, if ["$ A"-ge "$ B"] -Lt is less than, for example, if ["$ A"-lt "$ B"] -Le is less than or equal to, for example, if ["$ A"-Le "$ B"] <Less than (double parentheses are required), such as: ("$ A" <"$ B ")) <= Less than or equal to (double parentheses are required), for example: ("$ A" <= "$ B ")) > Greater than (double parentheses are required), such as: ("$ A"> "$ B ")) > = Equal to or greater than (double parentheses required), for example: ("$ A"> = "$ B ")) String comparison -------------------------------------------------------- = Equals, for example, if ["$ A" = "$ B"] = Equal to, such as: If ["$ A" = "$ B"], equivalent to = Note: The = function has different behaviors in [[] and [], as shown below: 1 [[$ A = z *] # True if $ A starts with "Z" (pattern matching) 2 [[$ A = "z *"] # If $ A is equal to z * (character matching), the result is true. 3 4 [$ A = z *] # file globbing and word splitting will occur 5 ["$ A" = "z *"] # If $ A is equal to z * (character matching), the result is true. For a bit of explanation, file globbing is a stenographer of files, for example, "*. c" is, and then ~ Yes. But file globbing is not a strict regular expression, although the structure is similar in most cases. ! = Not equal to, such as: If ["$ "! = "$ B"] This operator uses pattern matching in the [[] structure. <Less than, in the ASCII alphabetic order. For example: If [["$ A" <"$ B"] If ["$ A" \ <"$ B"] Note: "<" must be escaped in the [] structure. > Greater than, in the ASCII alphabetic order. For example: If [["$ A"> "$ B"] If ["$ A" \> "$ B"] Note: ">" needs to be escaped in the [] structure. For more information, see Example 26-11. -Z string is "null". The length is 0. -N string is not "null" Note: To use-N in the [] structure, you must use "" To cause variables. Use a string that is not! -Z Or the strings that are not referenced by "" are put in the [] structure. In general Work, but this is not safe. It is a good habit to use "" To test strings. String Splitting: Var = 'echo "AAA, BBB, CCC" | awk-F', ''{print $2 }'' Echo $ VaR