shell scripting single for loop how to get a output from a file

Question

Source file data.txt

A
B
.
.
.
Z

Source file contain A to Z write each character in one line each.

Result Need

A_01
A_02
.
.
.
A_26
B_01
.
.
B_26
.
.
.
Z_01
.
.
Z_26

Note: from the source file we need to count the no.of line and add that number to each split character.

I got a Solution But I need to do in one for statement.

end=`wc -l data.txt | awk '{print $1}'`

for i in $(cat data.txt )
do
  for j in `seq $end`
  do
    echo "$i"_"$j"
  done 
done

the tag [shell] is generic, and doesn't tell us what implementation you are using. Most likely [bash], so please add a tag for your shell of preference. Search your shell's documentation for math operations. Good luck. — shellter
– shellter, Commented Jul 11, 2019 at 12:13
You can mention that A..Z are example values, you don't want printf "%s\n" {A..Z}_{01..26}. — Walter A
– Walter A, Commented Jul 11, 2019 at 13:04
Another nit-pick: but the use of backticks is discouraged. It's legacy, and non-POSIX. There's a number of reasons why the $() notation is preferred see some here — Elias Van Ootegem
– Elias Van Ootegem, Commented Jul 11, 2019 at 15:02

kvantour · Accepted Answer · 2019-07-11 13:08:20Z

1

awk '{for(i=1;i<=NR-FNR;i++) print $0,i}' OFS='_' file file

The reason this works is because NR-FNR is always zero for the first read of the file, while it is always 26 for the second read of the file.

edited Jul 11, 2019 at 13:08

answered Jul 11, 2019 at 12:56

kvantour

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Comments

ceving · Accepted Answer · 2019-07-11 13:13:06Z

1

Bash has a function called mapfile, to read a file in an array.

mapfile -t data < data.txt
numbers=($(seq -f '%02.0f' "${#data[@]}"))
for line in "${data[@]}"; do
  printf "${line}_%s\n" "${numbers[@]}"
done

answered Jul 11, 2019 at 13:13

ceving

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Comments

kvantour · Accepted Answer · 2019-07-11 13:51:04Z

0

If you are ok with awk, could you please try following.

awk -v line=$(wc -l < Input_file) '{for(i=1;i<=line;i++) printf("%s_%02d\n",$0,i)}' Input_file

edited Jul 11, 2019 at 13:51

kvantour

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answered Jul 11, 2019 at 12:24

RavinderSingh13

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4 Comments

Arun Solomon Over a year ago

Ans is almost correct but I need is A_01...A_26...Z_01..Z_26

Arun Solomon Over a year ago

No. bro Same result like this showing A_1...A_26 want A_01

RavinderSingh13 Over a year ago

@ArunSolomon, Give it sometime and when you have few answers, you could select anyone of them as correct one too. I saw your profile and realize that you don't do that often, cheers and happy learning.

tripleee Over a year ago

Not my downvote, but the wc -l strikes me as inelegant. You can store the file in memory, or read the file twice, and solve this in pure Awk.

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