The use of grep the author proposes will have each line of output prefixed with the name of the file it came from followed by a colon. That is if the glob expan

The use of grep the author proposes will have each line of output prefixed with the name of the file it came from followed by a colon. That is if the glob expands to more than one file though, if it only expands to a single file then it is equivalent to cat. Use of the -h option should be passed to grep if the difference in format is something the author wishes to guarantee.