The " egrep" variant supports an extended regular expression syntax added by Alfred Aho after Ken Thompson's original regular expression implementation. Early variants included egrep and fgrep, introduced in Version 7 Unix.
#NODEBOX SAME NAME DIFFRENT NODE SOFTWARE#
Root:x:0:0:root:/root:/bin/bash operator:x:11:0:operator:/root:/sbin/nologin $ grep -n root /etc/passwdġ:root:x:0:0:root:/root:/bin/bash 12:operator:x:11:0:operator:/root:/sbin/nologin $ grep -c false /etc/passwdĪ variety of grep implementations are available in many operating systems and software development environments. The following example demonstrates the output of the grep command given different arguments: Stating that it is "generally cited as the prototypical software tool", McIlroy credited grep with "irrevocably ingraining" Thompson's tools philosophy in Unix. grep was first included in Version 4 Unix. He chose the name because in ed, the command g/re/p would print all lines matching a specified pattern.
The ed text editor (also authored by Thompson) had regular expression support but could not be used on such a large amount of text, so Thompson excerpted that code into a standalone tool. McMahon analyze the text of The Federalist Papers to determine authorship of the individual papers. Thompson wrote the first version in PDP-11 assembly language to help Lee E. Thompson's account may explain the belief that grep was written overnight. The next day he presented the program to McIlroy, who said it was exactly what he wanted. 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"). Doug McIlroy, unaware of its existence, asked Thompson to write such a program. Before it was named, grep was a private utility written by Ken Thompson to search files for certain patterns.
0 kommentar(er)
