Assume a multi-line text file (file) and the keyword bar.
> cat file
foo bar baz
foo bar quux
foo quux bar
Each line that ends with the keyword shall be prepended with the string Hello; each line that does not shall be printed as is.
> cat file | sought_command
foo bar baz
foo bar quux
Hello foo quux bar
I believe that this can be done via awk (something along the lines of awk '$ ~ /bar/ {print "Hello", $0}'), but I cannot come up with the correct code and would appreciate suggestions.
You are almost on the right track using Awk, just use the regex anchor $ to mark the end the line, and append the string as needed,
awk '$NF == "bar"{$0="Hello"FS$0}1' file
This will append string only to those lines having keyword in the last.