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reversing a line

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# 1  
Old 06-02-2009
reversing a line
Hi,

I could not find this anywhere and I am wondering if someone knows a quick way of doing this.

So heres the problem... I have a row that looks like this (an example):

5 4 3 2 1

What I want to do is reverse it so it looks like this:

1 2 3 4 5

Does anyone know the simple unix command for this?

thanks
# 2  
Old 06-02-2009
One way to do it:

Code:
$
$ cat input.txt
5 4 3 2 1
$
$ perl -ne 'chomp; print scalar reverse, "\n"' input.txt
1 2 3 4 5
$

tyler_durden
# 3  
Old 06-02-2009
Code:
# echo "5 4 3 2 1" | awk 'BEGIN{FS=""}{for(i=NF;i>0;i--){printf $i}}'
1 2 3 4 5

# 4  
Old 06-03-2009
Code:
echo "5 4 3 2 1" | rev
1 2 3 4 5

# 5  
Old 06-03-2009
Not a good approach but works

$
Code:
echo "5 4 3 2 1" | sed 's/\([^ ]*\) \([^ *]\) \([^ ]*\) \([^ ]*\) \([^ ]*\)/\
5 \4 \3 \2 \1/g'

1 2 3 4 5

-Devaraj Takhellambam
# 6  
Old 06-03-2009
Quote:
Originally Posted by devtakh
Not a good approach but works

$
Code:
echo "5 4 3 2 1" | sed 's/\([^ ]*\) \([^ *]\) \([^ ]*\) \([^ ]*\) \([^ ]*\)/\
5 \4 \3 \2 \1/g'

1 2 3 4 5

-Devaraj Takhellambam
info sed, look for examples
# 7  
Old 06-03-2009
Quote:
Originally Posted by ghostdog74
Code:
# echo "5 4 3 2 1" | awk 'BEGIN{FS=""}{for(i=NF;i>0;i--){printf $i}}'
1 2 3 4 5

ghostdog74,

I don't get the right output with your solution, am I missing something?
Another one:

Code:
awk '{while (NF){printf("%s%s", $(NF--),!NF?"":FS)}}'
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