You want to check if a file data.txt exists and is not empty before processing it in a script. Which condition correctly does this?

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Bash Scripting - Conditionals

You want to check if a file data.txt exists and is not empty before processing it in a script. Which condition correctly does this?

A[ -f data.txt ] && [ -s data.txt ]

B[ -f data.txt -o -s data.txt ]

C[ -f data.txt && -s data.txt ]

D[ -f data.txt ] || [ -s data.txt ]

Step-by-Step Solution

Solution:

Step 1: Understand the tests
-f checks if file exists and is regular file; -s checks if file size is greater than zero (not empty).
Step 2: Choose correct logical operator
To require both conditions, use logical AND. Inside a single [ ], use -a; or chain separate tests with &&. Using && directly inside [ ] causes syntax error.
Step 3: Analyze options
The option with && inside single [ ] has syntax error. Chained tests with && are clear and reliable. Options using -o or || apply OR logic, incorrect.
Final Answer:
[ -f data.txt ] && [ -s data.txt ] -> Option A
Quick Check:
Use && to combine separate [ ] tests [OK]

Quick Trick: Use separate [ ] with && for AND conditions [OK]

Common Mistakes:

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