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Print words starting at particular positions

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# 1  
Old 10-22-2013
Print words starting at particular positions
I have three words say abc def and ghi. I want to write them in a text file each starting (not ending) at particular positions say 1, 42 and 73. It is guaranteed that they will not overwrite.

Length of the three variable may vary.

Any help?
# 2  
Old 10-22-2013
This would be simple in something like perl or python or even C, but shell doesn't support this directly.

You can abuse the dd utility to do this, though it's not the most efficient form of access.

Code:
printf "%s" "abc "| dd of=myfile bs=1 conv=notrunc seek=42

Untested, so back up your file before you try this.
# 3  
Old 10-22-2013
Thanks. But this is not what I want. The output will be a single line consisting of values of abc, def and ghi starting at particular positions say 1, 42 and 73. (If I have to pring ending at those positions, printf command is handy). Use of awk is also fine.
# 4  
Old 10-22-2013
Quote:
Originally Posted by Soham
I have three words say abc def and ghi. I want to write them in a text file each starting (not ending) at particular positions say 1, 42 and 73. It is guaranteed that they will not overwrite.

Length of the three variable may vary.

Any help?
Code:
a="abc"
b="def"
c="ghi"
printf "%-41s%-31s%s\n" $a $b $c

Read up on printf to see what is happening, but basically I am telling it to left-justify the strings in the fields of the given lengths.

Andrew
This User Gave Thanks to apmcd47 For This Post:
Soham
# 5  
Old 10-22-2013
Try this:

Code:
$ cat infile
test one
12345678901234567890123456789012345678901234567890123456789012345678901234567890
two

$ awk '
 BEGIN{
    R[1]="abc"
    R[42]="def"
    R[73]="ghi"
    w=75}
 { if(length<w) $0=sprintf("%-"w"s", $0);
  for(r in R) $0 = substr($0,1,r-1) R[r] substr($0,r + length(R[r]))}1' infile
abct one                                 def                            ghi
abc45678901234567890123456789012345678901def5678901234567890123456789012ghi67890
abc                                      def                            ghi

---------- Post updated at 09:45 AM ---------- Previous update was at 08:12 AM ----------

Another approach is to define a function to do the work and call it as required, the output of this solution should be the same as the earlier one, it just might be a little easier to read/change/comment:

Code:
awk '
function overlay(s,f,v) {return substr(sprintf("%-*s",length(v)+f,s),1,f-1) v substr(s,f+length(v)) }
{
 $0 = overlay($0,  1, "abc")
 $0 = overlay($0, 42, "def")
 $0 = overlay($0, 73, "ghi")
}1' infile

This User Gave Thanks to Chubler_XL For This Post:
Soham
# 6  
Old 10-23-2013
Thanks apmcd47 and Chubler_XL. Works nice.
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