Question
In a POSIX shell script, which construct correctly tests
whether variable x is an empty string?Solution
-z returns true if string length is zero; quoting $x avoids word-splitting when empty.
More Shell Scripting Questions
sin2 7 ° + sin2 8 ° + sin2 9 ° + sin2 10 ° + ……… + sin2 83 ° = ?
...Simplify the following trigonometric expression: 12 cos 68° cosec 22° - 3 cot 72° cot 18°
...If cos2B = sin(1.5B + 48o), then find the measure of 'B'.
The value of sec2 45˚ + 2 tan 135˚ is –
- If X = 15°, find the value of:
sin²(4X) + cos²(3X) - tan²(2X) Two points P and Q are at the distance of x and y (where y > x) respectively from the base of a building and on a straight line. If the angles of elevat...
- If sin (2A − 3B) = (1/2) and cos (A + B) = (√3/2), where 0° < A, B < 90°, then find the value of ‘A’.
If sin (2x + 50) o = cos (2y - 50) o, such that, 0o < x + y < 90o, then find the value of tan(x + y) .
If 3 tan X + cot X = 2√3, then find the value of 6 tan2 X + 2 cot2 X.
