using awk to print header name and a substring - bash

Question

i try using this code for printing a header of a gene name and then pulling a substring based on its location but it doesn't work
>output_file
cat input_file | while read row; do
echo $row > temp
geneName=`awk '{print $1}' tmp`
startPos=`awk '{print $2}' tmp`
endPOs=`awk '{print $3}' tmp`
for i in temp; do
echo ">${geneName}" >> genes_fasta ;
echo "awk '{val=substr($0,${startPos},${endPOs});print val}' fasta" >> genes_fasta
done
done
input_file
nad5_exon1 250405 250551
nad5_exon2 251490 251884
nad5_exon3 195620 195641
nad5_exon4 154254 155469
nad5_exon5 156319 156548
fasta
atgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgc............
and this is my wrong output file
>
awk '{val=substr(pull_genes.sh,,);print val}' unwraped_carm_mt.fasta
>
awk '{val=substr(pull_genes.sh,,);print val}' unwraped_carm_mt.fasta
>
awk '{val=substr(pull_genes.sh,,);print val}' unwraped_carm_mt.fasta
>
awk '{val=substr(pull_genes.sh,,);print val}' unwraped_carm_mt.fasta
>
awk '{val=substr(pull_genes.sh,,);print val}' unwraped_carm_mt.fasta
>
awk '{val=substr(pull_genes.sh,,);print val}' unwraped_carm_mt.fasta
output should look like that:
>name1
atgcatgcatgcatgcatgcat
>name2
tgcatgcatgcatgcat
>name3
gcatgcatgcatgcatgcat
>namen....

Answer 1

You can do this with a single call to awk which will be orders of magnitude more efficient than looping in a shell script and calling awk 4-times per-iteration. Since you have bash, you can simply use command substitution and redirect the contents of fasta to an awk variable and then simply output the heading and the substring containing the beginning through ending characters from your fasta file.
For example:
awk -v fasta=$(<fasta) '{print ">" $1; print substr(fasta,$2,$3-$2+1)}' input
or using getline within the BEGIN rule:
awk 'BEGIN{getline fasta<"fasta"}
{print ">" $1; print substr(fasta,$2,$3-$2+1)}' input
Example Input Files
Note: the beginning and ending values have been reduced to fit within the 129 characters of your example:
$ cat input
rad5_exon1 1 17
rad5_exon2 23 51
rad5_exon3 110 127
rad5_exon4 38 62
rad5_exon5 59 79
and the first 129-characters of your example fasta
$ cat fasta
atgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgcatgc
Example Use/Output
$ awk -v fasta=$(<fasta) '{print ">" $1; print substr(fasta,$2,$3-$2+1)}' input
>rad5_exon1
atgcatgcatgcatgca
>rad5_exon2
gcatgcatgcatgcatgcatgcatgcatg
>rad5_exon3
tgcatgcatgcatgcatg
>rad5_exon4
tgcatgcatgcatgcatgcatgcat
>rad5_exon5
gcatgcatgcatgcatgcatg
Look thing over and let me know if I understood your question requirements. Also let me know if you have further questions on the solution.

Answer 2

If I'm understanding correctly, how about:
awk 'NR==FNR {fasta = fasta $0; next}
{
printf(">%s %s\n", $1, substr(fasta, $2, $3 - $2 + 1))
}' fasta input_file > genes_fasta
It first reads fasta file and stores the sequence in a variable fasta.
Then it reads input_file line by line, extracts the substring of fasta starting at $2 and of length $3 - $2 + 1. (Note that the 3rd argument to substr function is length, not endpos.)
Hope this helps.

Answer 3

made it work!
this is the script for pulling substrings from a fasta file
cat genes_and_bounderies1 | while read row; do
echo $row > temp
geneName=`awk '{print $1}' temp`
startPos=`awk '{print $2}' temp`
endPos=`awk '{print $3}' temp`
length=$(expr $endPos - $startPos)
for i in temp; do
echo ">${geneName}" >> genes_fasta
awk -v S=$startPos -v L=$length '{print substr($0,S,L)}' unwraped_${fasta} >> genes_fasta
done
done