while read line

 while read line

cat peptides.txt | while read line 
do
   # do something with $line here
   echo $line
done

for, for_each (Terraform), until ... do, while ... do

while

Bash [ -c ], alias, &&, Bash history, Autocompletion, set, unset, export, .bash_aliases, .bashrc and .bash profile, PS1, echo, brace expansion, Function, shopt, trap, set -e, source, PATH, complete, disown, .hushlogin, .bashrc, builtin, eval, set, $PATH, $HOME, TZ, .profile, -e, -i, Builtin (Bash), mapfile, ~, return (Bash), for, until, declare, dirname, basename, functions.sh, Bash arithmetic expansion, shift, bash --rcfile, readonly, $1, $@