1) Print the first three exon records in ecoli.gff3 in a single command
head -n 3 <( grep "exon" ecoli.gff3 ) ## redirect input for the head command to be a grep for exon
grep "exon" ecoli.gff3 | head -n 3 ## Or pipe the output of grep exon into the head command
2) For each record, only print the name value Name=MJ49_RS00725; => MJ49_RS00725
grep -o "Name=[^;]\+" ecoli.gff3 | grep -o "[^Name=]\+" ## first search for all values where Name=*something*, then search for characters that don't match "Name="
3) Count how many basepairs are in ecoli.fasta.
grep -v ">" ecoli.fasta | wc -c ## we don't want to count descriptive characters, for a fasta all non-sequence lines start with ">" so first we filter those out, then count the characters
5583275