Small question with the sort command

Bleek · 12-05-2009, 02:21 PM

Quote:

Originally Posted by pixellany

I seem to remember you were just looking for a way to print the first line.... How about:
sed -n '1p'

Did you look at the sed instructions?

I did, but there's ALOT to look through... I tried:
sort -n numbers | sed -n 1p numbers > largest
sort -n numbers | sed -n 1p > largest

Neither worked... I'll keep trying!

pixellany · 12-05-2009, 02:35 PM

I created a file (num) with 5 numbers.

Code:

[mherring@Ath play]$ more num
34
5
6
9
15
[mherring@Ath play]$ sort -n num
5
6
9
15
34
[mherring@Ath play]$ sort -n num|sed -n '$p'
34
[mherring@Ath play]$ sort -r -n num|sed -n '1p'
34

One example prints the LAST line
The second example does a reverse sort and prints the FIRST line.

You will find all this in the man pages and other documents.

Tinkster · 12-05-2009, 03:59 PM

Quote:

Originally Posted by Bleek

I did, but there's ALOT to look through... I tried:
sort -n numbers | sed -n 1p numbers > largest
sort -n numbers | sed -n 1p > largest

Neither worked... I'll keep trying!

Out of curiosity: what WERE the results of those commands
of yours, what did you get in the file 'largest'? I would
have expected the last one to work.

Cheers,
Tink

johnsfine · 12-05-2009, 06:16 PM

Quote:

Originally Posted by johnsfine

There is an old joke about needing instructions on the bottom of a beer bottle saying "open other end".

Have you considered changing your sort command?

Quote:

Originally Posted by Bleek

What would I change it to?

I didn't think it needed further explanation.

Sort so the largest value is the last line. Pipe that to tail to copy just the last line to the destination file.

Bleek · 12-05-2009, 06:21 PM

Quote:

Originally Posted by Tinkster

Out of curiosity: what WERE the results of those commands
of yours, what did you get in the file 'largest'? I would
have expected the last one to work.

Cheers,
Tink

Well the program won't allow me to tinker with its insides (it's basically a program where you write in the answer and won't let you do anything else). Anyway I made a file to try this out myself, within numbers I had:
8
32
21
31
500
43

And when I used 'sort -n numbers | sed -n 1p > largest' it ended up being exactly the same.

When I used 'sort -n numbers | sed -n 1p > largest' the result in 'numbers' was 8. So it seems that my sort command isn't working, which makes no sense to me as it looks fine. Any idea on what's wrong?

Quote:

Originally Posted by johnsfine

I didn't think it needed further explanation.

Sort so the largest value is the last line. Pipe that to tail to copy just the last line to the destination file.

Sadly it seems I have an inherit need to make things as complicated as possible, I'll try that out.

pixellany · 12-05-2009, 06:32 PM

Quote:

And when I used 'sort -n numbers | sed -n 1p > largest' it ended up being exactly the same.

I feel like I have stepped into the twilight zone.....

sort -n puts the largest value last. So sed '1p' will give you the smallest value. Is your system somehow different???

EDIT---maybe "sort" is aliased to something else????

Tinkster · 12-06-2009, 03:25 AM

Quote:

I feel like I have stepped into the twilight zone.....

sort -n puts the largest value last. So sed '1p' will give you the smallest value. Is your system somehow different???

EDIT---maybe "sort" is aliased to something else????

Nuh .. it's all good, we're both blind :}

It does exactly what we tell it to. Sort gives him 500 as the
last, but with sed we print the first line only, which will be
the smallest number - 8 in his case. The "trick" would be to
actually do the $p rather than 1p ;}

Cheers,
Tink

catkin · 12-06-2009, 04:49 AM

Code:

read largest <<< $(sort -nr numbers)
echo $largest > largest