How to Count Lines in a File on Linux: wc, grep, awk, and Compressed Files

Need to see how much the log grew overnight. Or verify a CSV has the right number of records before import. Or confirm a config was not truncated during copy. Line count is a quick, useful metric — and Linux has several ways to get it.

wc -l: The Main Tool

wc (word count) counts lines, words, and characters. The -l flag outputs lines only:

wc -l filename.txt

42 filename.txt

To get only the number without the filename — use a redirect:

wc -l < filename.txt

42

The difference matters in scripts: the first form always appends the filename to output, the second returns the number alone.

Multiple Files and a Total

Count lines in several files at once:

wc -l file1.txt file2.txt file3.txt

  120 file1.txt
   85 file2.txt
  204 file3.txt
  409 total

wc automatically adds a total line. Useful for a quick summary across a group of logs.

By pattern — all .log files in a directory:

wc -l /var/log/nginx/*.log

Recursively across all files in a directory:

find /var/log -name "*.log" -exec wc -l {} +

grep -c: Lines Matching a Pattern

grep -c counts only lines that match a pattern, not all lines:

grep -c "ERROR" /var/log/app.log

Count lines with today's date:

grep -c "$(date +%Y-%m-%d)" /var/log/syslog

To count all lines through grep — use an empty pattern:

grep -c "" filename.txt

An empty pattern matches every line.

awk: Count With Conditions

awk counts lines through the built-in NR (number of records) variable:

awk 'END {print NR}' filename.txt

Count only non-empty lines:

awk 'NF' filename.txt | wc -l

NF (number of fields) is zero for empty lines — awk skips them.

Count lines longer than 80 characters:

awk 'length > 80 {count++} END {print count}' filename.txt

sed: Quick Counter

sed with -n and the $= command prints the line number of the last line — equivalent to the total line count:

sed -n '$=' filename.txt

Compact and fast, especially on large files.

Count Lines in a Compressed File

Logs are often stored gzipped. Read without decompressing:

zcat /var/log/syslog.1.gz | wc -l

For .bz2:

bzcat file.bz2 | wc -l

Count Lines in Command Output

Count running processes:

ps aux | wc -l

Count open connections on port 80:

ss -tn | grep ':80' | wc -l

Count files in a directory:

ls /var/www/html | wc -l

Edge Case: File Without Trailing Newline

wc -l counts \n characters. If a file ends without a newline, the last line is not counted. This matters for files generated by programs.

Check whether the file ends with a newline:

tail -c 1 filename.txt | xxd

If output is empty — the file ends with \n. If a character appears — there is no trailing newline and wc -l undercounts by one.

Quick Reference