Differences between revisions 35 and 36
Revision 35 as of 2008-11-08 01:03:28
Size: 1733
Editor: GreyCat
Comment:
Revision 36 as of 2008-11-08 02:20:56
Size: 372
Editor: CPE0007e944c43c-CM001ac352c6bc
Comment: -9
Deletions are marked like this. Additions are marked like this.
Line 1: Line 1:
[[Anchor(faq19)]]
== How can I split a file into line ranges, e.g. lines 1-10, 11-20, 21-30? ==
Some Unix systems provide the {{{split}}} utility for this purpose:

{{{
    split --lines 10 --numeric-suffixes input.txt output-
}}}

For more flexibility you can use {{{sed}}}. The {{{sed}}} command can print e.g. the line number range 1-10:
{{{
    sed -n -e '1,10p' -e '10q'
}}}

This stops {{{sed}}} from printing each line ({{{-n}}}). Instead it only processes the lines in the range 1-10 ("1,10"), and prints them ("p"). The command will quit after reading line 10 ("10q").

We can now use this to print an arbitrary range of a file (specified by line number):

{{{
# POSIX shell
file=/etc/passwd
range=10
cur=1
last=$(wc -l < "$file") # count number of lines
chunk=1
while [ $cur -lt $last ]
do
    endofchunk=$(($cur + $range - 1))
    sed -n -e "$cur,${endofchunk}p" -e "${endofchunk}q" "$file" > chunk.$(printf %04d $chunk)
    chunk=$(($chunk + 1))
    cur=$(($cur + $range))
done
}}}

The previous example uses POSIX [:ArithmeticExpression:arithmetic], which older [:BourneShell:Bourne shells] do not have. In that case the following example should be used instead:

{{{
# legacy Bourne shell; assume no printf either
file=/etc/passwd
range=10
cur=1
last=`wc -l < "$file"` # count number of lines
chunk=1
while test $cur -lt $last
do
    endofchunk=`expr $cur + $range - 1`
    sed -n -e "$cur,${endofchunk}p" -e "${endofchunk}q" "$file" > chunk.$chunk
    chunk=`expr $chunk + 1`
    cur=`expr $cur + $range`
done
}}}

Awk can also be used to produce a more or less equivalent result:

{{{
 awk -v range=10 '{print > FILENAME "." (int((NR -1)/ range)+1)}' file
}}}
Wow! my name is Martin Pua, I'm from Uruguay and I'm 20 years old. recipe ingredient vanilla pudding Brilliant but simple idea. http://list21.bplaced.net/recipe4292.html cake recipes with shortening seem, http://redndo.9ix.net/recipe9137.html cornflake peanut butter balls recipe salt, http://and82.myd.net/recipe520.html baking recipes, Shrug.
----
CategoryCategory

Wow! my name is Martin Pua, I'm from Uruguay and I'm 20 years old. recipe ingredient vanilla pudding Brilliant but simple idea. http://list21.bplaced.net/recipe4292.html cake recipes with shortening seem, http://redndo.9ix.net/recipe9137.html cornflake peanut butter balls recipe salt, http://and82.myd.net/recipe520.html baking recipes, Shrug.


CategoryCategory

BashFAQ/019 (last edited 2022-04-19 12:13:19 by emanuele6)