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grep is a command-line utility for searching plaintext datasets for lines that match a regular expression. Its name comes from the ed command g/re/p (global regular expression search and print), which has the same effect.
--lines = count The number of lines printed may be changed with a command line option. The following example shows the first 20 lines of filename: head -n 20 filename. This displays the first 5 lines of all files starting with foo: head -n 5 foo* Most versions [citation needed] allow omitting n and instead directly specifying the number: -5.
The command has a number of switches: a - number all lines; t - number lines with printable text only; n - no line numbering; string - number only those lines containing the regular expression defined in the string supplied. The default applied switch is t. nl also supports some command line options.
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]
Checksums (IEEE Ethernet CRC-32) and count the bytes in a file. Supersedes other *sum utilities with -a option from version 9.0. comm: Compares two sorted files line by line csplit: Splits a file into sections determined by context lines cut: Removes sections from each line of files expand: Converts tabs to spaces fmt: Simple optimal text ...
Select or reject lines common to two files ... grep: Misc Mandatory Search text for a pattern ... Line, word and byte or character count Version 1 AT&T UNIX what:
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.
Extraction of line segments can typically be done by bytes (-b), characters (-c), or fields (-f) separated by a delimiter (-d — the tab character by default). A range must be provided in each case which consists of one of N, N-M, N-(N to the end of the line), or -M (beginning of the line to M), where N and M are counted from 1 (there is no ...