format String using sed

Question

How to format the following input strings to output strings using sed?

The center string should start at 20th character and end string should start at 40th character.

input:

begining center end     
beg12  cen12  end12
beg13 cen  end

output:

begining     center      end     
beg12        cen12       end12
beg13        cen         end

Answer 1

awk may be used to format this data with its printf() function.

$ awk '{ printf("%-20s%-20s%s\n", $1, $2, $3) }' data.in
begining            center              end
beg12               cen12               end12
beg13               cen                 end

This assumes that the data in the file is whitespace-separated.

To give it the column width as a parameter:

$ cols=40
$ awk -v c="$cols" 'BEGIN { fmt=sprintf("%%-%ds%%-%ds%%s\n", c, c) } { printf(fmt, $1, $2, $3) }' data.in
begining                                center                                  end
beg12                                   cen12                                   end12
beg13                                   cen                                     end

Answer 2

This is one of those occasions where I wouldn't use sed, I would use printf, particularly the
%-Ns format which will pad the string with blanks until the "field" occupies a minimum of N characters

#!/usr/bin/env bash

while read first second third
do
    printf "%-20s%-20s%s\n" "$first" "$second" "$third"
done <<- 'EOF' 
    begining center end     
    beg12  cen12  end12
    beg13 cen  end
EOF

Answer 3

awk approach:

awk '{printf("%-20s%-20s%-20s\n",$1,$2,$3)}' file

The output:

begining            center              end                 
beg12               cen12               end12               
beg13               cen                 end 

Answer 4

You already got answers with other tools, column being the most obvious. I agree that sed is not the tool of choice for this, but if you already use sed to get the table, it's nasty to pipe that output to another tool just for formatting. In this case use something like this at the end of your script:

sed 's/  */    /g;s/ /     /g;s/\(.\{20\}\) */\1/g'

This replaces all groups of spaces by four spaces, then each space by five spaces, so we have padded 20 spaces. The third s command keeps the first 20 chars of each column and removes remaining spaces.

Answer 5

< yourfile tr -s '\t ' '\t\t' | expand -t 19,39

---

Results

         1         2         3         4         5
12345678901234567890123456789012345678901234567890
begining           center              end
beg12              cen12               end12
beg13              cen                 end

---

Working

• First we squeeze out all residual spaces and/or TABs to TABs only.
• Then we apply the expand command on the resultant by using the -t option and listing out the tab positions.

Answer 6

sed 's/  */    /g;s/ /     /g;s/\(.\{20\}\) */\1/g' 

-> This gives space in every word.

beginning and end has only one word. center has multiple words.

beginning          center cntr cnt center              end
beg12              cen12  cnt cntr                     end12
beg13              cen center                          end