Interview Q&A / Linux & Shell

1. How do you search for text and files in Linux using grep and find?

   grep searches inside files for lines matching a pattern, for example grep -rn "error" logs/. find searches the directory tree for files by name, type, size or age, for example find . -name "*.log" -mtime -1. They are often combined to search text inside a chosen set of files.

   BeginnerIn-depth2 min read
2. What do the grep options -i, -v, -c, -n and -w do?

   -i ignores case, -v inverts the match to show non-matching lines, -c prints only a count of matching lines, -n adds line numbers and -w matches whole words only. They combine, so grep -ivn error file works.

   BeginnerQuick answer1 min read
3. When do you need grep -E, and what is the difference from basic grep patterns?

   Basic grep treats +, ?, | and () as ordinary characters unless escaped. grep -E (extended regex) gives them their regex meaning, so grep -E 'cat|dog' matches either word. Use -F when you want a plain fixed string with no regex at all.

   IntermediateQuick answer1 min read