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The pcregrep command is an implementation of grep that uses Perl regular expression syntax. [17] Similar functionality can be invoked in the GNU version of grep with the -P flag. [18] Ports of grep (within Cygwin and GnuWin32, for example) also run under Microsoft Windows. Some versions of Windows feature the similar qgrep or findstr command. [19]
This is a list of commands from the GNU Core Utilities for Unix environments. These commands can be found on Unix operating systems and most Unix-like operating systems. GNU Core Utilities include basic file, shell and text manipulation utilities. Coreutils includes all of the basic command-line tools that are expected in a POSIX system.
These commands can be found on Unix operating systems and most Unix-like operating systems. This is not a comprehensive list of all utilities that existed in the various historic Unix and Unix-like systems, as it excludes utilities that were not mandated by the aforementioned standard.
grep is a command-line utility for searching plain-text data sets for lines matching a regular expression and by default reporting matching lines on standard output. tree is a command-line utility that recursively lists files found in a directory tree, indenting the filenames according to their position in the file hierarchy.
The book starts off with an introduction to Unix for beginners. Next, it goes into the basics of the file system and shell.The reader is led through topics ranging from the use of filters, to how to use C for programming robust Unix applications, and the basics of grep, sed, make, and AWK.
He later added this capability to the Unix editor ed, which eventually led to the popular search tool grep's use of regular expressions ("grep" is a word derived from the command for regular expression searching in the ed editor: g/re/p meaning "Global search for Regular Expression and Print matching lines"). [15]
The non-interactive Unix command grep was inspired by a common special use of qed and later ed, where the command g/re/p performs a global regular expression search and prints the lines containing matches. The Unix stream editor, sed implemented many of the scripting features of qed that were not supported by ed on Unix. [6] [failed ...
An important aspect of this, setting Unix pipes apart from other pipe implementations, is the concept of buffering: for example a sending program may produce 5000 bytes per second, and a receiving program may only be able to accept 100 bytes per second, but no data is lost. Instead, the output of the sending program is held in the buffer.