Question at position 9 Given the following shell variable assignments, a=2; b=5; c=10 Which of the following conditions is true? [ $a –eq 3 –o $b –ge 5 ][ $b –gt 5 ][ $c = (3 + 7) ][ a –eq 2 ]单项选择题
A
[ $a –eq 3 –o $b –ge 5 ]
B
[ $b –gt 5 ]
C
[ $c = (3 + 7) ]
D
[ a –eq 2 ]

Question

Question at position 9 Given the following shell variable assignments, a=2; b=5; c=10 Which of the following conditions is true? [ $a –eq 3 –o $b –ge 5 ][ $b –gt 5 ][ $c = (3 + 7) ][ a –eq 2 ]单项选择题

A

[ $a –eq 3 –o $b –ge 5 ]

B

[ $b –gt 5 ]

C

[ $c = (3 + 7) ]

D

[ a –eq 2 ]

BlackTom AI · Accepted Answer

We start by restating the scenario: a=2; b=5; c=10, and we must evaluate each shell test condition.
Option 1: [ $a –eq 3 –o $b –ge 5 ]
Here, the first part tests if a equals 3, which is false since a=2. The second part tests if b is greater than or equal to 5, which is true since b=5. The -o operator means logical OR, so the overall expression is true because at least one side is true.
Option 2: [ $b –gt 5 ]
This checks if b is greater than 5. Since b=5, the comparison is false. There is no other part to rescue the truth value, so the whole condition is false.
Option 3: [ $c = (3 + 7) ]
This attempts to compare c to the string (3 + 7). In POSIX test, without arithmetic expansion, the right-hand side is treated as a literal string. Since c is 10, the string "10" does not equal the string "(3 + 7)", so this evaluates to false. Also, even if arithmetic expansion occurred, the syntax would require $((3+7)) and the current form does not perform that arithmetic expansion.
Option 4: [ a –eq 2 ]
Here, the left-hand side is the literal character a, not the value of the variable a (which would be $a). Since a is not substituted, the test tries to perform numeric comparison -eq on the string "a", which is invalid for integer comparison and typically yields an error, making the condition false in practical shell execution. Additionally, even if it were parsed as a string, -eq is an arithmetic operator, not a string comparison, so this is semantically incorrect.
In summary, Option 1 yields a true result due to the second sub-condition being true, while Options 2, 3, and 4 fail to be true for the given variable values and typical test semantics. Thus, the only true condition among the choices is the first one.