Bash Scripting - Loops
You want to write a script that waits until a file named
done.txt exists before continuing. Which until loop is correct?You want to write a script that waits until a file named done.txt exists before continuing. Which until loop is correct?
hard🚀 Application Q8 of 15
Step-by-Step Solution
Solution:
Step 1: Understand the goal
The script should wait until the file exists, so it should loop while the file does not exist.Step 2: Choose correct condition
until [ -f done.txt ]; do echo "Waiting..."; sleep 1; done loops while [ -f done.txt ] returns non-zero (file missing), stopping when the condition returns zero (file exists).Final Answer:
until [ -f done.txt ]; do echo "Waiting..."; sleep 1; done -> Option AQuick Check:
Loop runs while file missing, stops when file exists [OK]
Quick Trick: Use until [ -f file ] to loop while file missing [OK]
Common Mistakes:
MISTAKES- Using -d for file instead of -f
- Using ! -f which reverses the logic
Master "Loops" in Bash Scripting
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