On Unix/Linux, which command is used to sort the lines of a file in ascending (alphabetical/lexicographic) order?

Introduction / Context:
Sorting text is a common step in log analysis, report preparation, and data cleaning. The standard 'sort' utility orders lines lexicographically by default and can be tuned for numeric sorts, locale specifics, and key-based ordering, making it a versatile tool for shell pipelines and scripts.

Given Data / Assumptions:

• You have a plain-text file containing multiple lines.
• You want the default ascending ordering.
• No special collation or key selection is required.

Concept / Approach:
Running 'sort filename' outputs lines in ascending order according to the system's locale. You can adjust behavior with options such as '-n' for numeric sort, '-k' to select sort keys, and '-r' for reverse order. Combining these options yields powerful one-liners for complex sorting tasks.

Step-by-Step Solution:

Verification / Alternative check:
Compare the output of 'sort' with an editor's sorted view, or use 'uniq' afterwards to collapse duplicates if de-duplication is also desired. For numeric data, verify that '-n' is used; otherwise 10 may appear before 2 due to string comparison rules.

Why Other Options Are Wrong:

• sort - r: Represents reverse sorting (and contains a spacing error); it is not the default ascending order.
• sh: Invokes the shell, not a sorting utility.
• st: Not a standard Unix command.
• None of the above: Incorrect because 'sort' is correct.

Common Pitfalls:
Forgetting '-n' for numeric fields, ignoring locale effects on ordering, or sorting the wrong column when working with delimited data without specifying '-k' and '-t' properly.

Final Answer:
sort