Longest line in a file

I'm looking for a simple way to find the length of the longest line in a file. Ideally, it would be a simple bash开发者_如何学编程 shell command instead of a script.

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Using wc (GNU coreutils) 7.4:

wc -L filename

gives:

101 filename

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

For reference : Finding the longest line in a file

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

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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"

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wc -L < filename

gives

101

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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

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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

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Important overlooked point in the above examples.

The following 2 examples count expanded tabs

  wc -L  <"${SourceFile}" 
# or
  expand --tabs=8 "${SourceFile}" | awk '{ if (length($0) > max) {max = length($0)} } END { print max }'

The following 2 count non expaned tabs.

  expand --tabs=1 "${SourceFile}" | wc -L 
# or
  awk '{ if (length($0) > max) {max = length($0)} } END { print max }' "${SourceFile}"

so

              Expanded    nonexpanded
$'nn\tnn'       10            5

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In perl:

perl -ne 'print ($l = $_) if (length > length($l));' filename | tail -1

this only prints the line, not its length too.

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Here are references of the anwser

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

http://wtanaka.com/node/7719

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Just for fun, here's the Powershell version:

cat filename.txt | sort length | select -last 1

And to just get the length:

(cat filename.txt | sort length | select -last 1).Length

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I'm in a Unix environment, and work with gzipped files that are a few GBs in size. I tested the following commands using a 2 GB gzipped file with record length of 2052.

1. zcat <gzipped file> | wc -L

and

2. zcat <gzipped file> | awk '{print length}' | sort -u

The times were on avarage

1. 117 seconds

2. 109 seconds

Here is my script after about 10 runs.

START=$(date +%s) ## time of start

zcat $1 |  wc -L

END=$(date +%s) ## time of end
DIFF=$(( $END - $START ))
echo "It took $DIFF seconds"

START=$(date +%s) ## time of start

zcat $1 |  awk '{print length}' | sort -u

END=$(date +%s) ## time of end
DIFF=$(( $END - $START ))
echo "It took $DIFF seconds"

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Variation on the theme.

This one will show all lines having the length of the longest line found in the file, retaining the order they appear in the source.

FILE=myfile grep `tr -c "\n" "." < $FILE | sort | tail -1` $FILE

So myfile

x
mn
xyz
123
abc

will give

xyz
123
abc

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If you are using MacOS and are getting this error: wc: illegal option -- L you dont need to install GNU sipmly do this.

If all you want to do is just get the count of the characters in the longest line of the file and you are using OS X run:

awk '{print length}' "$file_name" | sort -rn | head -1

Something like this;

echo "The longest line in the file $file_name has $(awk '{print length}' "$file_name" | sort -rn | head -1) characters"

Outputs:

The longest line in the file my_file has 117 characters