Question 1

What operations are available for processing lines of text?

Accepted Answer

Common line utilities: sort lines (alphabetical, numerical, reverse), remove duplicate lines (deduplicate), remove empty/blank lines, reverse line order, shuffle lines randomly, prefix/suffix each line, trim whitespace from each line, filter lines matching a pattern, number each line, extract specific lines by range, and join lines with a delimiter. These operations are the building blocks of data cleaning and text transformation workflows.

Question 2

What is the difference between sort and unique in line operations?

Accepted Answer

Sort reorders lines alphabetically or numerically without removing anything. Unique (deduplicate) removes lines that appear more than once — either the second occurrence only or all duplicates. Sort + Unique together is a classic Unix pattern: sort | uniq (or sort -u) produces a sorted list with duplicates removed. Case sensitivity matters: 'Apple' and 'apple' are treated as duplicates in case-insensitive mode but not in case-sensitive mode.

Question 3

How do I sort and deduplicate lines in the terminal?

Accepted Answer

Unix commands: sort file.txt (sort alphabetically), sort -n file.txt (sort numerically), sort -r file.txt (reverse), sort -u file.txt (sort and remove duplicates), sort file.txt | uniq -c (count occurrences), sort file.txt | uniq -d (only lines that appear more than once), sort file.txt | uniq -u (only lines that appear exactly once). For Windows PowerShell: Get-Content file.txt | Sort-Object -Unique. These are standard tools available on any Unix/Linux/macOS system.

Question 4

How do I remove empty lines from text?

Accepted Answer

In the terminal: grep -v '^$' file.txt (removes lines with no characters), grep -v '^\s*$' file.txt (removes lines with only whitespace). In JavaScript: text.split('
').filter(line => line.trim() !== '').join('
'). In Python: '
'.join(line for line in text.splitlines() if line.strip()). In VS Code: open the Find dialog with regex enabled, search for ^
 (or ^
 on Windows), replace with nothing. This is one of the most common text cleanup tasks.

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