Linux CLI - Text Processing
You want to print the second field only for lines where the first field starts with 'a' or 'b'. Which awk command achieves this?
You want to print the second field only for lines where the first field starts with 'a' or 'b'. Which awk command achieves this?
hard📝 Application Q15 of 15
Step-by-Step Solution
Solution:
Step 1: Understand pattern for fields starting with 'a' or 'b'
The regex /^[ab]/ matches strings starting with 'a' or 'b'. The operator ~ means regex match.Step 2: Check each option's correctness
awk '$1 ~ /^[ab]/ {print $2}' file.txt uses correct regex and syntax. awk '$1 == "a" || $1 == "b" {print $2}' file.txt compares whole field to 'a' or 'b' exactly, not starts with. awk '$1 = "a" || $1 = "b" {print $2}' file.txt uses assignment '=' instead of comparison '=='. awk '$1 ~ /a|b/ {print $2}' file.txt matches anywhere 'a' or 'b' appears, not just start.Final Answer:
awk '$1 ~ /^[ab]/ {print $2}' file.txt -> Option AQuick Check:
Regex match start with a or b = awk '$1 ~ /^[ab]/ {print $2}' file.txt [OK]
Quick Trick: Use regex ^[ab] to match start of field [OK]
Common Mistakes:
- Using = instead of == for comparison
- Matching exact string instead of start
- Using wrong regex without ^ anchor
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