Shulou(Shulou.com)06/02 Report--

This article mainly introduces what Shell expressions and operators have. The introduction in the article is very detailed and has certain reference value. Interested friends must read it!

3.1 conditional expression

expression

example

[ expression ][ 1 -eq 1 ]` expression `` 1 -eq 1 `test expressiontest 1 -eq 1 , equivalent to []

3.2 integer comparator

comparison operator

described

example

-eq, equal to [ 1 -eq 1 ] for true-ne, not equal to [ 1 -ne 1 ] for false-gt, greater than [ 2 -gt 1 ] for true-lt, lesser than [ 2 -lt 1 ] for false-ge, greater or equal to [ 2 -gt 1 ] for true-le, lesser or equal to [ 2 -le 1 ] for false

3.3 string comparator

operator

described

example

====[ "a" == "a" ] is true!= is not equal to [ "a" != "a" ] is false> greater than, judging strings according to ASCII code table order, rarely used

In [] expression: [ 2 \> 1 ] is true

In [[]] expression: [[ 2 > 1 ]] is true

In the expression (()):(( 3 > 2 )) is true

= greater than or equal to In the expression (()):(( 3 >= 2 )) is true

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