Q283302

grep is a command-line utility for searching text for lines that match a regular expression. Its name comes from the ed command g/re/p (global, regular expression, print), which has the same effect. grep was originally developed for the Unix operating system, and is commonly available on Unix-like and some other systems such as OS-9. The shell command that runs the utility has the same name: .

==History== Before it was named, grep was a private utility written by Ken Thompson to search files for certain patterns. Doug McIlroy, unaware of its existence, asked Thompson to write such a program. Responding that he would think about such a utility overnight, Thompson actually corrected bugs and made improvements for about an hour on his own program called s (short for "search"). The next day he presented the program to McIlroy, who said it was exactly what he wanted. Thompson's account may explain the belief that grep was written overnight.