问题
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 shell command instead of a script.
回答1:
Using wc (GNU coreutils) 7.4:
wc -L filename
gives:
101 filename
回答2:
awk '{print length, $0}' Input_file |sort -nr|head -1
For reference : Finding the longest line in a file
回答3:
awk '{ if (length($0) > max) {max = length($0); maxline = $0} } END { print maxline }' YOURFILE
回答4:
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"
回答5:
wc -L < filename
gives
101
回答6:
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$_ is the current line
回答7:
Important overlooked point in the above examples.
The following 2 examples count expanded tabs
wc -L <"${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
回答8:
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: " $1 " length_with_line_number: " length}' | sort -k4 -nr | head -3
longest_line_number: 3 length_with_line_number: 13
longest_line_number: 4 length_with_line_number: 12
longest_line_number: 2 length_with_line_number: 11
回答9:
In perl:
perl -ne 'print ($l = $_) if (length > length($l));' filename | tail -1
this only prints the line, not its length too.
回答10:
Here are references of the anwser
cat filename | awk '{print length, $0}'|sort -nr|head -1
http://wtanaka.com/node/7719
回答11:
Just for fun, here's the Powershell version:
cat filename.txt | sort length | select -last 1
And to just get the length:
(cat filename.txt | sort length | select -last 1).Length
回答12:
I'm in a Unix environment, and work with gzipped files that are a few GBs in size. I tested the following commands using a 2 GB gzipped file with record length of 2052.
zcat <gzipped file> | wc -L
and
zcat <gzipped file> | awk '{print length}' | sort -u
The times were on avarage
117 seconds
109 seconds
Here is my script after about 10 runs.
START=$(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"
回答13:
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` $FILE
So myfile
x
mn
xyz
123
abc
will give
xyz
123
abc
回答14:
If you are using MacOS and are getting this error:
wc: illegal option -- L you dont need to install GNU sipmly do this.
If all you want to do is just get the count of the characters in the longest line of the file and you are using OS X run:
awk '{print length}' "$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
来源：https://stackoverflow.com/questions/1655372/longest-line-in-a-file