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Size: 1735
Comment: spam
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Size: 1955
Comment: quote expansions where necessary and don't use `$' in arithmetic contexts
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| Deletions are marked like this. | Additions are marked like this. |
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| Some Unix systems provide the {{{split}}} utility for this purpose: | POSIX specifies the {{{split}}} utility, which can be used for this purpose: |
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| {{{ split --lines 10 --numeric-suffixes input.txt output- |
{{{#!highlight bash split -l 10 input.txt |
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| {{{ sed -n -e '1,10p' -e '10q' |
{{{#!highlight bash sed 10q # Print lines 1-10 and then quit. sed '1,5d; 10q' # Print just lines 6-10 by filtering the first 5 then quitting after 10. |
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| 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"). | The `d` command stops {{{sed}}} from printing each line. This could alternatively have been done by passing sed the `-n` option and printing lines with the `p` command rather than deleting them with `d`. It makes no difference. |
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| {{{ | {{{#!highlight bash |
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| while [ $cur -lt $last ] | while [ "$cur" -lt "$last" ] |
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| endofchunk=$(($cur + $range - 1)) | endofchunk=$((cur + range - 1)) |
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| chunk=$(($chunk + 1)) cur=$(($cur + $range)) |
chunk=$((chunk + 1)) cur=$((cur + range)) |
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| {{{ | {{{#!highlight bash |
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| while test $cur -lt $last | while test "$cur" -lt "$last" |
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| sed -n -e "$cur,${endofchunk}p" -e "${endofchunk}q" "$file" > chunk.$chunk | sed -n -e "$cur,${endofchunk}p" -e "${endofchunk}q" "$file" > "chunk.$chunk" |
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| {{{ awk -v range=10 '{print > FILENAME "." (int((NR -1)/ range)+1)}' file |
{{{#!highlight bash awk -v range=10 '{print > FILENAME "." (int((NR -1)/ range)+1)}' file |
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---- CategoryShell |
How can I split a file into line ranges, e.g. lines 1-10, 11-20, 21-30?
POSIX specifies the split utility, which can be used for this purpose:
1 split -l 10 input.txt
For more flexibility you can use sed. The sed command can print e.g. the line number range 1-10:
The d command stops sed from printing each line. This could alternatively have been done by passing sed the -n option and printing lines with the p command rather than deleting them with d. It makes no difference.
We can now use this to print an arbitrary range of a file (specified by line number):
1 # POSIX shell
2 file=/etc/passwd
3 range=10
4 cur=1
5 last=$(wc -l < "$file") # count number of lines
6 chunk=1
7 while [ "$cur" -lt "$last" ]
8 do
9 endofchunk=$((cur + range - 1))
10 sed -n -e "$cur,${endofchunk}p" -e "${endofchunk}q" "$file" > chunk.$(printf %04d $chunk)
11 chunk=$((chunk + 1))
12 cur=$((cur + range))
13 done
The previous example uses POSIX arithmetic, which older Bourne shells do not have. In that case the following example should be used instead:
1 # legacy Bourne shell; assume no printf either
2 file=/etc/passwd
3 range=10
4 cur=1
5 last=`wc -l < "$file"` # count number of lines
6 chunk=1
7 while test "$cur" -lt "$last"
8 do
9 endofchunk=`expr $cur + $range - 1`
10 sed -n -e "$cur,${endofchunk}p" -e "${endofchunk}q" "$file" > "chunk.$chunk"
11 chunk=`expr $chunk + 1`
12 cur=`expr $cur + $range`
13 done
Awk can also be used to produce a more or less equivalent result:
1 awk -v range=10 '{print > FILENAME "." (int((NR -1)/ range)+1)}' file