Longest line in a file

Question

Using wc (GNU coreutils) 7.4:

wc -L filename

gives:

101 filename

awk '{print length, $0}' Input_file |sort -nr|head -1

For reference : Finding the longest line in a file

awk '{ if (length($0) > max) {max = length($0); maxline = $0} } END { print maxline }'  YOURFILE 

Just for fun and educational purpose, the pure POSIX shell solution, without useless use of cat and no forking to external commands. Takes filename as first argument:

#!/bin/sh

MAX=0 IFS=
while read -r line; do
  if [ ${#line} -gt $MAX ]; then MAX=${#line}; fi
done < "$1"
printf "$MAX\n"

wc -L < filename

gives

101

perl -ne 'print length()."  line $.  $_"' myfile | sort -nr | head -n 1

Prints the length, line number, and contents of the longest line

perl -ne 'print length()."  line $.  $_"' myfile | sort -n

Prints a sorted list of all lines, with line numbers and lengths

. is the concatenation operator - it is used here after length()
$. is the current line number
$_ is the current line

Looks all the answer do not give the line number of the longest line. Following command can give the line number and roughly length:

$ cat -n test.txt | awk '{print "longest_line_number: " $1 " length_with_line_number: " length}' | sort -k4 -nr | head -3
longest_line_number: 3 length_with_line_number: 13
longest_line_number: 4 length_with_line_number: 12
longest_line_number: 2 length_with_line_number: 11