How can I extract a predetermined range of lines from a text file on Unix?

Question

I have a ~23000 line SQL dump containing several databases worth of data. I need to extract a certain section of this file (i.e. the data for a single database) and place it in a new file. I know both the start and end line numbers of the data that I want.

Does anyone know a Unix command (or series of commands) to extract all lines from a file between say line 16224 and 16482 and then redirect them into a new file?

Answer 1

sed -n '16224,16482 p' orig-data-file > new-file

Where 16224,16482 are the start line number and end line number, inclusive. This is 1-indexed. -n suppresses echoing the input as output, which you clearly don't want; the numbers indicate the range of lines to make the following command operate on; the command p prints out the relevant lines.

Answer 2

Quite simple using head/tail:

head -16482 in.sql | tail -258 > out.sql

using sed:

sed -n '16224,16482p' in.sql > out.sql

using awk:

awk 'NR>=16224&&NR<=16482' in.sql > out.sql

Answer 3

You could use 'vi' and then the following command:

:16224,16482w!/tmp/some-file

Alternatively:

cat file | head -n 16482 | tail -n 258

EDIT:- Just to add explanation, you use head -n 16482 to display first 16482 lines then use tail -n 258 to get last 258 lines out of the first output.

Answer 4

There is another approach with awk:

awk 'NR==16224, NR==16482' file

If the file is huge, it can be good to exit after reading the last desired line. This way, it won't read the following lines unnecessarily:

awk 'NR==16224, NR==16482-1; NR==16482 {print; exit}' file

awk 'NR==16224, NR==16482; NR==16482 {exit}' file

Answer 5

perl -ne 'print if 16224..16482' file.txt > new_file.txt

Answer 6

Standing on the shoulders of boxxar, I like this:

sed -n '<first line>,$p;<last line>q' input

e.g.

sed -n '16224,$p;16482q' input

The $ means "last line", so the first command makes sed print all lines starting with line 16224 and the second command makes sed quit after printing line 16428. (Adding 1 for the q-range in boxxar's solution does not seem to be necessary.)

I like this variant because I don't need to specify the ending line number twice. And I measured that using $ does not have detrimental effects on performance.

Answer 7

 # print section of file based on line numbers
 sed -n '16224 ,16482p'               # method 1
 sed '16224,16482!d'                 # method 2

Answer 8

People trying to wrap their heads around computing an interval for the head | tail combo are overthinking it.

Here's how you get the "16224 -- 16482" range without computing anything:

cat file | head -n +16482 | tail -n +16224

---

Explanation:

• The + instructs the head/tail command to "go up to / start from" (respectively) the specified line number as counted from the beginning of the file.

• Similarly, a - instructs them to "go up to / start from" (respectively) the specified line number as counted from the end of the file

• The solution shown above simply uses head first, to 'keep everything up to the top number', and then tail second, to 'keep everything from the bottom number upwards', thus defining our range of interest (with no need to compute an interval).

Answer 9

cat dump.txt | head -16224 | tail -258

should do the trick. The downside of this approach is that you need to do the arithmetic to determine the argument for tail and to account for whether you want the 'between' to include the ending line or not.

Answer 10

sed -n '16224,16482p' < dump.sql

Answer 11

Quick and dirty:

head -16428 < file.in | tail -259 > file.out

Probably not the best way to do it but it should work.

BTW: 259 = 16482-16224+1.

Answer 12

I wrote a Haskell program called splitter that does exactly this: have a read through my release blog post.

You can use the program as follows:

$ cat somefile | splitter 16224-16482

And that is all that there is to it. You will need Haskell to install it. Just:

$ cabal install splitter

And you are done. I hope that you find this program useful.

Answer 13

Even we can do this to check at command line:

cat filename|sed 'n1,n2!d' > abc.txt

For Example:

cat foo.pl|sed '100,200!d' > abc.txt

Answer 14

Using ruby:

ruby -ne 'puts "#{$.}: #{$_}" if $. >= 32613500 && $. <= 32614500' < GND.rdf > GND.extract.rdf

Answer 15

I wanted to do the same thing from a script using a variable and achieved it by putting quotes around the $variable to separate the variable name from the p:

sed -n "$first","$count"p imagelist.txt >"$imageblock"

I wanted to split a list into separate folders and found the initial question and answer a useful step. (split command not an option on the old os I have to port code to).

Answer 16

Just benchmarking 3 solutions given above, that works to me:

• awk
• sed
• "head+tail"

Credits on the 3 solutions goes to:

• @boxxar
• @avandeursen
• @wds
• @manveru
• @sibaz
• @SOFe
• @fedorqui 'SO stop harming'
• @Robin A. Meade

---

I'm using a huge file I find in my server:

# wc fo2debug.1.log
   10421186    19448208 38795491134 fo2debug.1.log

38 Gb in 10.4 million lines.

And yes, I have a logrotate problem. : ))

---

Make your bets!

---

Getting 256 lines from the beginning of the file.

# time sed -n '1001,1256p;1256q' fo2debug.1.log | wc -l
256

real    0m0,003s
user    0m0,000s
sys     0m0,004s

# time head -1256 fo2debug.1.log | tail -n +1001 | wc -l
256

real    0m0,003s
user    0m0,006s
sys     0m0,000s

# time awk 'NR==1001, NR==1256; NR==1256 {exit}' fo2debug.1.log | wc -l
256

real    0m0,002s
user    0m0,004s
sys     0m0,000s

Awk won. Technical tie in second place between sed and "head+tail".

---

Getting 256 lines at the end of the first third of the file.

# time sed -n '3473001,3473256p;3473256q' fo2debug.1.log | wc -l
256

real    0m0,265s
user    0m0,242s
sys     0m0,024s

# time head -3473256 fo2debug.1.log | tail -n +3473001 | wc -l
256

real    0m0,308s
user    0m0,313s
sys     0m0,145s

# time awk 'NR==3473001, NR==3473256; NR==3473256 {exit}' fo2debug.1.log | wc -l
256

real    0m0,393s
user    0m0,326s
sys     0m0,068s

Sed won. Followed by "head+tail" and, finally, awk.

---

Getting 256 lines at the end of the second third of the file.

# time sed -n '6947001,6947256p;6947256q' fo2debug.1.log | wc -l
A256

real    0m0,525s
user    0m0,462s
sys     0m0,064s

# time head -6947256 fo2debug.1.log | tail -n +6947001 | wc -l
256

real    0m0,615s
user    0m0,488s
sys     0m0,423s

# time awk 'NR==6947001, NR==6947256; NR==6947256 {exit}' fo2debug.1.log | wc -l
256

real    0m0,779s
user    0m0,650s
sys     0m0,130s

Same results.

Sed won. Followed by "head+tail" and, finally, awk.

---

Getting 256 lines near the end of the file.

# time sed -n '10420001,10420256p;10420256q' fo2debug.1.log | wc -l
256

real    1m50,017s
user    0m12,735s
sys     0m22,926s

# time head -10420256 fo2debug.1.log | tail -n +10420001 | wc -l
256

real    1m48,269s
user    0m42,404s
sys     0m51,015s

# time awk 'NR==10420001, NR==10420256; NR==10420256 {exit}' fo2debug.1.log | wc -l
256

real    1m49,106s
user    0m12,322s
sys     0m18,576s

And suddenly, a twist!

"Head+tail" won. Followed by awk and, finally, sed.

---

(some hours later...)

Sorry guys!

My analysis above ends up being an example of a basic flaw in doing an analysis.

The flaw is not knowing in depth the resources used for the analysis.

In this case, I used a log file to analyze the performance of a search for a certain number of lines within it.

Using 3 different techniques, searches were made at different points in the file, comparing the performance of the techniques at each point and checking whether the results varied depending on the point in the file where the search was made.

My mistake was to assume that there was a certain homogeneity of content in the log file.

The reality is that long lines appear more frequently at the end of the file.

Thus, the apparent conclusion that longer searches (closer to the end of the file) are better with a given technique, may be biased. In fact, this technique may be better when dealing with longer lines. What remains to be confirmed.

Answer 17

I was about to post the head/tail trick, but actually I'd probably just fire up emacs. ;-)

1. esc-x goto-line ret 16224
2. mark (ctrl-space)
3. esc-x goto-line ret 16482
4. esc-w

open the new output file, ctl-y save

Let's me see what's happening.

Answer 18

I would use:

awk 'FNR >= 16224 && FNR <= 16482' my_file > extracted.txt

FNR contains the record (line) number of the line being read from the file.

Answer 19

Using ed:

ed -s infile <<<'16224,16482p'

-s suppresses diagnostic output; the actual commands are in a here-string. Specifically, 16224,16482p runs the p (print) command on the desired line address range.

Answer 20

I wrote a small bash script that you can run from your command line, so long as you update your PATH to include its directory (or you can place it in a directory that is already contained in the PATH).

Usage: $ pinch filename start-line end-line

#!/bin/bash
# Display line number ranges of a file to the terminal.
# Usage: $ pinch filename start-line end-line
# By Evan J. Coon

FILENAME=$1
START=$2
END=$3

ERROR="[PINCH ERROR]"

# Check that the number of arguments is 3
if [ $# -lt 3 ]; then
    echo "$ERROR Need three arguments: Filename Start-line End-line"
    exit 1
fi

# Check that the file exists.
if [ ! -f "$FILENAME" ]; then
    echo -e "$ERROR File does not exist. \n\t$FILENAME"
    exit 1
fi

# Check that start-line is not greater than end-line
if [ "$START" -gt "$END" ]; then
    echo -e "$ERROR Start line is greater than End line."
    exit 1
fi

# Check that start-line is positive.
if [ "$START" -lt 0 ]; then
    echo -e "$ERROR Start line is less than 0."
    exit 1
fi

# Check that end-line is positive.
if [ "$END" -lt 0 ]; then
    echo -e "$ERROR End line is less than 0."
    exit 1
fi

NUMOFLINES=$(wc -l < "$FILENAME")

# Check that end-line is not greater than the number of lines in the file.
if [ "$END" -gt "$NUMOFLINES" ]; then
    echo -e "$ERROR End line is greater than number of lines in file."
    exit 1
fi

# The distance from the end of the file to end-line
ENDDIFF=$(( NUMOFLINES - END ))

# For larger files, this will run more quickly. If the distance from the
# end of the file to the end-line is less than the distance from the
# start of the file to the start-line, then start pinching from the
# bottom as opposed to the top.
if [ "$START" -lt "$ENDDIFF" ]; then
    < "$FILENAME" head -n $END | tail -n +$START
else
    < "$FILENAME" tail -n +$START | head -n $(( END-START+1 ))
fi

# Success
exit 0

Answer 21

This might work for you (GNU sed):

sed -ne '16224,16482w newfile' -e '16482q' file

or taking advantage of bash:

sed -n $'16224,16482w newfile\n16482q' file

Answer 22

Since we are talking about extracting lines of text from a text file, I will give an special case where you want to extract all lines that match a certain pattern.

myfile content:
=====================
line1 not needed
line2 also discarded
[Data]
first data line
second data line
=====================
sed -n '/Data/,$p' myfile

Will print the [Data] line and the remaining. If you want the text from line1 to the pattern, you type: sed -n '1,/Data/p' myfile. Furthermore, if you know two pattern (better be unique in your text), both the beginning and end line of the range can be specified with matches.

sed -n '/BEGIN_MARK/,/END_MARK/p' myfile

Answer 23

The -n in the accept answers work. Here's another way in case you're inclined.

cat $filename | sed "${linenum}p;d";

This does the following:

1. pipe in the contents of a file (or feed in the text however you want).
2. sed selects the given line, prints it
3. d is required to delete lines, otherwise sed will assume all lines will eventually be printed. i.e., without the d, you will get all lines printed by the selected line printed twice because you have the ${linenum}p part asking for it to be printed. I'm pretty sure the -n is basically doing the same thing as the d here.

Answer 24

I was looking for an answer to this but I had to end up writing my own code which worked. None of the answers above were satisfactory. Consider you have very large file and have certain line numbers that you want to print out but the numbers are not in order. You can do the following:

My relatively large file for letter in {a..k} ; do echo $letter; done | cat -n > myfile.txt

 1  a
 2  b
 3  c
 4  d
 5  e
 6  f
 7  g
 8  h
 9  i
10  j
11  k

Specific line numbers I want: shuf -i 1-11 -n 4 > line_numbers_I_want.txt

 10
 11
 4
 9

To print these line numbers, do the following. awk '{system("head myfile.txt -n " $0 " | tail -n 1")}' line_numbers_I_want.txt

What the above does is to head the n line then take the last line using tail

If you want your line numbers in order, sort ( is -n numeric sort) first then get the lines.

cat line_numbers_I_want.txt | sort -n | awk '{system("head myfile.txt -n " $0 " | tail -n 1")}'

 4  d
 9  i
10  j
11  k

Answer 25

Maybe, you would be so kind to give this humble script a chance ;-)

#!/usr/bin/bash

# Usage:
#   body n m|-m

from=$1
to=$2

if [ $to -gt 0 ]; then
# count $from the begin of the file $to selected line
    awk "NR >= $from && NR <= $to {print}"
else
# count $from the begin of the file skipping tailing $to lines
    awk '
    BEGIN   {lines=0; from='$from'; to='$to'}
            {++lines}
    NR >= $from {line[lines]=$0}
    END     {for (i = from; i < lines + to + 1; i++) {
                print line[i]
            }
    }'
fi

Outputs:

$ seq 20 | ./body.sh 5 15
5
6
7
8
9
10
11
12
13
14
15

$ seq 20 | ./body.sh 5 -5
5
6
7
8
9
10
11
12
13
14
15

Answer 26

I've compiled some of the highest rated solutions for sed, perl, head+tail, plus my own code for awk, and focusing on performance via the pipe, while using LC_ALL=C to ensure all candidates at their fastest possible, allocating 2-second sleep gap in between.

The gaps are somewhat noticeable :

   abs time    awk/app speed ratio
 ----------------------------------
   0.0672 sec :   1.00x mawk-2
   0.0839 sec :   1.25x gnu-sed
   0.1289 sec :   1.92x perl
   0.2151 sec :   3.20x gnu-head+tail

Haven't had chance to test python or BSD variants of those utilities.

 (fg && fg && fg && fg) 2>/dev/null; 
 echo;
 ( time ( pvE0 < "${m3t}" 
        | LC_ALL=C  mawk2 '

           BEGIN {  
                     _=10420001-(\
                    __=10420256)^(FS="^$") 
           } _<NR { 
                   print

                   if(__==NR) { exit } 
     
     }' ) | pvE9) | tee >(xxh128sum >&2) | LC_ALL=C gwc -lcm | lgp3 ; 
    sleep 2;
    (fg && fg && fg && fg) 2>/dev/null
    echo; 
    ( time ( pvE0 < "${m3t}" 
           | LC_ALL=C gsed -n '10420001,10420256p;10420256q' 
    
     ) | pvE9 ) |  tee >(xxh128sum >&2) |  LC_ALL=C gwc -lcm  | lgp3 ;
     sleep  2; (fg && fg && fg && fg) 2>/dev/null
     echo
    ( time ( pvE0 < "${m3t}" 
           | LC_ALL=C perl -ne 'print if 10420001..10420256'
    
    ) | pvE9 ) |  tee >(xxh128sum >&2) |  LC_ALL=C gwc -lcm | lgp3 ;
    sleep  2; (fg && fg && fg && fg) 2>/dev/null
    echo
    ( time ( pvE0 < "${m3t}" 
           | LC_ALL=C ghead -n +10420256 
           | LC_ALL=C gtail -n +10420001 
    ) | pvE9 ) |  tee >(xxh128sum >&2) |  LC_ALL=C gwc -lcm  | lgp3 ; 


      in0: 1.51GiB 0:00:00 [2.31GiB/s] [2.31GiB/s] [============> ] 81%            
     out9: 42.5KiB 0:00:00 [64.9KiB/s] [64.9KiB/s] [ <=> ]
( pvE 0.1 in0 < "${m3t}" | LC_ALL=C mawk2 ; )
     
   0.43s user 0.36s system 117% cpu 0.672 total
    256   43487   43487

54313365c2e66a48dc1dc33595716cc8  stdin

     out9: 42.5KiB 0:00:00 [51.7KiB/s] [51.7KiB/s] [ <=> ]
      in0: 1.51GiB 0:00:00 [1.84GiB/s] [1.84GiB/s] [==========> ] 81%            

   ( pvE 0.1 in0 < "${m3t}" |LC_ALL=C gsed -n '10420001,10420256p;10420256q'; )  
  
   0.68s user 0.34s system 121% cpu 0.839 total
    256   43487   43487

54313365c2e66a48dc1dc33595716cc8  stdin


      in0: 1.85GiB 0:00:01 [1.46GiB/s] [1.46GiB/s] [=============>] 100%            
     out9: 42.5KiB 0:00:01 [33.5KiB/s] [33.5KiB/s] [  <=> ]

( pvE 0.1 in0 < "${m3t}" | LC_ALL=C perl -ne 'print if 10420001..10420256'; )
     
   1.10s user 0.44s system 119% cpu 1.289 total
    256   43487   43487

54313365c2e66a48dc1dc33595716cc8  stdin

      in0: 1.51GiB 0:00:02 [ 728MiB/s] [ 728MiB/s] [=============> ] 81%            
     out9: 42.5KiB 0:00:02 [19.9KiB/s] [19.9KiB/s] [ <=> ]

 ( pvE 0.1 in0 < "${m3t}" 
   | LC_ALL=C ghead -n +10420256 
   | LC_ALL=C gtail -n ; )  
  
 1.98s user 1.40s system 157% cpu 2.151 total
 256   43487   43487

54313365c2e66a48dc1dc33595716cc8  stdin