Print text between two lines (from list of line numbers in file) in Unix [closed] - shell

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Closed 9 years ago.
I have a sample file which has thousands of lines.
I want to print text between two line numbers in that file. I don't want to input line numbers manually, rather I have a file which contains list of line numbers between which text has to be printed.
Example : linenumbers.txt
345|789
999|1056
1522|1366
3523|3562
I need a shell script which will read line numbers from this file and print the text between each range of lines into a separate (new) file.
That is, it should print lines between 345 and 789 into a new file, say File1.txt, and print text between lines 999 and 1056 into a new file, say File2.txt, and so on.

Answer 1

considering your target file has only thousands of lines. here is a quick and dirty solution.
awk -F'|' '{system("sed -n \""$1","$2"p\" targetFile > file"NR)}' linenumbers.txt
the targetFile is your file containing thousands of lines.
the oneliner does not require your linenumbers.txt to be sorted.
the oneliner allows line range to be overlapped in your linenumbers.txt
after running the command above, you will have n filex files. n is the row counts of linenumbers.txt x is from 1-n you can change the filename pattern as you want.

Answer 2

Here's one way using GNU awk. Run like:
awk -f script.awk numbers.txt file.txt
Contents of script.awk:
BEGIN {
# set the field separator
FS="|"
}
# for the first file in the arguments list
FNR==NR {
# add the row number and field one as keys to a multidimensional array with
# a value of field two
a[NR][$1]=$2
# skip processing the rest of the code
next
}
# for the second file in the arguments list
{
# for every element in the array's first dimension
for (i in a) {
# for every element in the second dimension
for (j in a[i]) {
# ensure that the first field is treated numerically
j+=0
# if the line number is greater than the first field
# and smaller than the second field
if (FNR>=j && FNR<=a[i][j]) {
# print the line to a file with the suffix of the first file's
# line number (the first dimension)
print > "File" i
}
}
}
}
Alternatively, here's the one-liner:
awk -F "|" 'FNR==NR { a[NR][$1]=$2; next } { for (i in a) for (j in a[i]) { j+=0; if (FNR>=j && FNR<=a[i][j]) print > "File" i } }' numbers.txt file.txt
If you have an 'old' awk, here's the version with compatibility. Run like:
awk -f script.awk numbers.txt file.txt
Contents of script.awk:
BEGIN {
# set the field separator
FS="|"
}
# for the first file in the arguments list
FNR==NR {
# add the row number and field one as a key to a pseudo-multidimensional
# array with a value of field two
a[NR,$1]=$2
# skip processing the rest of the code
next
}
# for the second file in the arguments list
{
# for every element in the array
for (i in a) {
# split the element in to another array
# b[1] is the row number and b[2] is the first field
split(i,b,SUBSEP)
# if the line number is greater than the first field
# and smaller than the second field
if (FNR>=b[2] && FNR<=a[i]) {
# print the line to a file with the suffix of the first file's
# line number (the first pseudo-dimension)
print > "File" b[1]
}
}
}
Alternatively, here's the one-liner:
awk -F "|" 'FNR==NR { a[NR,$1]=$2; next } { for (i in a) { split(i,b,SUBSEP); if (FNR>=b[2] && FNR<=a[i]) print > "File" b[1] } }' numbers.txt file.txt

Answer 3

I would use sed to process the sample data file because it is simple and swift. This requires a mechanism for converting the line numbers file into the appropriate sed script. There are many ways to do this.
One way uses sed to convert the set of line numbers into a sed script. If everything was going to standard output, this would be trivial. With the output needing to go to different files, we need a line number for each line in the line numbers file. One way to give line numbers is the nl command. Another possibility would be to use pr -n -l1. The same sed command line works with both:
nl linenumbers.txt |
sed 's/ *\([0-9]*\)[^0-9]*\([0-9]*\)|\([0-9]*\)/\2,\3w file\1.txt/'
For the given data file, that generates:
345,789w > file1.txt
999,1056w > file2.txt
1522,1366w > file3.txt
3523,3562w > file4.txt
Another option would be to have awk generate the sed script:
awk -F'|' '{ printf "%d,%dw > file%d.txt\n", $1, $2, NR }' linenumbers.txt
If your version of sed will allow you to read its script from standard input with -f - (GNU sed does; BSD sed does not), then you can convert the line numbers file into a sed script on the fly, and use that to parse the sample data:
awk -F'|' '{ printf "%d,%dw > file%d.txt\n", $1, $2, NR }' linenumbers.txt |
sed -n -f - sample.data
If your system supports /dev/stdin, you can use one of:
awk -F'|' '{ printf "%d,%dw > file%d.txt\n", $1, $2, NR }' linenumbers.txt |
sed -n -f /dev/stdin sample.data
awk -F'|' '{ printf "%d,%dw > file%d.txt\n", $1, $2, NR }' linenumbers.txt |
sed -n -f /dev/fd/0 sample.data
Failing that, use an explicit script file:
awk -F'|' '{ printf "%d,%dw > file%d.txt\n", $1, $2, NR }' linenumbers.txt > sed.script
sed -n -f sed.script sample.data
rm -f sed.script
Strictly, you should deal with ensuring the temporary file name is unique (mktemp) and removed even if the script is interrupted (trap):
tmp=$(mktemp sed.script.XXXXXX)
trap "rm -f $tmp; exit 1" 0 1 2 3 13 15
awk -F'|' '{ printf "%d,%dw > file%d.txt\n", $1, $2, NR }' linenumbers.txt > $tmp
sed -n -f $tmp sample.data
rm -f $tmp
trap 0
The final trap 0 allows your script to exit successfully; omit it, and you script will always exit with status 1.
I've ignored Perl and Python; either could be used for this in a single command. The file management is just fiddly enough that using sed seems simpler. You could also use just awk, either with a first awk script writing an awk script to do the heavy duty work (trivial extension of the above), or having a single awk process read both files and produce the required output (harder, but far from impossible).
If nothing else, this shows that there are many possible ways of doing the job. If this is a one-off exercise, it really doesn't matter very much which you choose. If you will be doing this repeatedly, then choose the mechanism that you like. If you're worried about performance, measure. It is likely that converting the line numbers into a command script is a negligible cost; processing the sample data with the command script is where the time is taken. I would expect sed to excel at that point; I've not measured to confirm that it does.

Answer 4

You could do the following
# myscript.sh
linenumbers="linenumber.txt"
somefile="afile"
while IFS=\| read start end ; do
echo "sed -n '$start,${end}p;${end}q;' $somefile > $somefile-$start-$end"
done < $linenumbers
run it like so sh myscript.sh
sed -n '345,789p;789q;' afile > afile-345-789
sed -n '999,1056p;1056q;' afile > afile-999-1056
sed -n '1522,1366p;1366q;' afile > afile-1522-1366
sed -n '3523,3562p;3562q;' afile > afile-3523-3562
then when you're happy do sh myscript.sh | sh
EDIT Added William's excellent points on style and correctness.
EDIT Explanation
The basic idea is to get a script to generate a series of shell commands that can be checked for correctness first before being executed by "| sh".
sed -n '345,789p;789q; means use sed and don't echo each line (-n) ; there are two commands saying from line 345 to 789 p(rint) the lines and the second command is at line 789 q(uit) - by quitting on the last line you save having sed read all the input file.
The while loop reads from the $linenumbers file using read, read if given more than one variable name populates each with a field from the input, a field is usually separated by space and if there are too few variable names then read will put the remaining data into the last variable name.
You can put the following in at your shell prompt to understand that behaviour.
ls -l | while read first rest ; do
echo $first XXXX $rest
done
Try adding another variable second to the above to see what happens then, it should be obvious.
The problem is your data is delimited by |s and that's where using William's suggestion of IFS=\| works as now when reading from the input the IFS has changed and the input is now separated by |s and we get the desired result.
Others can feel free to edit,correct and expand.

Answer 5

To extract the first field from 345|789 you can e.g use awk
awk -F'|' '{print $1}'
Combine that with the answers received from your other question and you will have a solution.

Answer 6

This might work for you (GNU sed):
sed -r 's/(.*)\|(.*)/\1,\2w file-\1-\2.txt/' | sed -nf - file