wc (Word Count)

# Count lines, words, and bytes in a file
wc filename.txt
# Output: 25 150 800 filename.txt
#        lines words bytes filename

# Count from standard input
echo "Hello world" | wc
# Output: 1 2 12

# Count lines in a file
wc -l filename.txt

# Count lines in multiple files
wc -l file1.txt file2.txt file3.txt

# Count lines from command output
ps aux | wc -l

# Count words in a file
wc -w document.txt

# Count words from input
echo "This is a test sentence" | wc -w
# Output: 5

# Count characters (multibyte aware)
wc -m filename.txt

# Count bytes
wc -c filename.txt

# Compare character vs byte count for UTF-8 file
wc -m utf8file.txt  # Character count
wc -c utf8file.txt  # Byte count (may be larger)

# Find the longest line in a file
wc -L filename.txt

# Find longest line in multiple files
wc -L *.txt

# Count statistics for multiple files
wc file1.txt file2.txt file3.txt
# Shows individual counts and total

# Count all text files
wc *.txt

# Recursive count of all files
find . -name "*.txt" -exec wc {} +

# Count log entries
wc -l /var/log/syslog

# Count error entries
grep "ERROR" /var/log/application.log | wc -l

# Count unique IP addresses in access log
awk '{print $1}' /var/log/apache2/access.log | sort -u | wc -l

# Count lines of code in Python files
find . -name "*.py" -exec wc -l {} + | tail -1

# Count total words in documentation
wc -w *.md | tail -1

# Count non-empty lines
grep -v '^$' filename.txt | wc -l

# Count records in CSV file
wc -l data.csv

# Count fields in first line (header)
head -1 data.csv | tr ',' '\n' | wc -l

# Count unique values in a column
cut -d',' -f2 data.csv | sort -u | wc -l

# Count processes
ps aux | wc -l

# Count files in directory
ls -1 | wc -l

# Count users logged in
who | wc -l

# Count network connections
netstat -tuln | wc -l

# Count words in specific pattern
grep "pattern" file.txt | wc -w

# Count lines containing specific text
grep -c "search_term" file.txt

# Count blank lines
grep -c '^$' file.txt

# Default output format
$ wc example.txt
  25  150  800 example.txt
  ^    ^    ^   ^
  |    |    |   filename
  |    |    byte count
  |    word count
  line count

# Multiple files with totals
$ wc file1.txt file2.txt
  10   50  250 file1.txt
  15   75  350 file2.txt
  25  125  600 total

# Empty file
wc empty.txt
# Output: 0 0 0 empty.txt

# File with only newlines
wc newlines.txt
# Output: 5 0 5 newlines.txt (5 lines, 0 words, 5 bytes)

# Binary file
wc binary_file
# Counts bytes, but word/line counts may not be meaningful

#!/bin/bash

# Store line count in variable
line_count=$(wc -l < filename.txt)
echo "File has $line_count lines"

# Check if file has content
if [ $(wc -l < file.txt) -gt 0 ]; then
    echo "File is not empty"
fi

# Compare file sizes
file1_lines=$(wc -l < file1.txt)
file2_lines=$(wc -l < file2.txt)
if [ $file1_lines -gt $file2_lines ]; then
    echo "file1.txt is larger"
fi

# Fast line counting (doesn't load entire file)
wc -l < largefile.txt

# Count only what you need
wc -l file.txt  # Faster than wc file.txt if you only need lines

# For very large files, consider alternatives
# Use grep -c for pattern counting
grep -c "pattern" hugefile.txt

# Different results between -c and -m
# This happens with multibyte characters (UTF-8)
wc -c utf8file.txt  # Byte count
wc -m utf8file.txt  # Character count

# No newline at end of file
# wc -l might show one less line than expected
echo -n "line without newline" | wc -l  # Shows 0

# Large files
# For very large files, wc might take time
# Consider using alternatives for specific patterns

# Count specific patterns
grep -c "pattern" file.txt

# Count unique lines
sort file.txt | uniq | wc -l

# Count files in directory
find /path -type f | wc -l

# Count with awk
awk 'END {print NR}' file.txt  # Line count
awk '{words += NF} END {print words}' file.txt  # Word count