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sed is a line-oriented text processing utility: it reads text, line by line, from an input stream or file, into an internal buffer called the pattern space. Each line read starts a cycle . To the pattern space, sed applies one or more operations which have been specified via a sed script . sed implements a programming language with about 25 ...
Boyer–Moore string-search algorithm; agrep, an approximate string-matching command; find (Windows) or Findstr, a DOS and Windows command that performs text searches, similar to a simple grep; find (Unix), a Unix command that finds files by attribute, very different from grep; List of Unix commands; vgrep, or "visual grep" ngrep, the network grep
In computer software, strings is a program in Unix, Plan 9, Inferno, and Unix-like operating systems that finds and prints the strings of printable characters in files. The files can be of regular text files or binary files such as executables.
(empty string) ε denoting the set containing only the "empty" string, which has no characters at all. ( literal character ) a in Σ denoting the set containing only the character a . Given regular expressions R and S, the following operations over them are defined to produce regular expressions:
In computer science, the Knuth–Morris–Pratt algorithm (or KMP algorithm) is a string-searching algorithm that searches for occurrences of a "word" W within a main "text string" S by employing the observation that when a mismatch occurs, the word itself embodies sufficient information to determine where the next match could begin, thus bypassing re-examination of previously matched characters.
We assume all the substrings have a fixed length m. A naïve way to search for k patterns is to repeat a single-pattern search taking O(n+m) time, totaling in O((n+m)k) time. In contrast, the above algorithm can find all k patterns in O(n+km) expected time, assuming that a hash table check works in O(1) expected time.
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.
A grammar that generates only a single string, as required for the solution to this problem, is called a straight-line grammar. [ 3 ] Every binary string of length n {\displaystyle n} has a grammar of length O ( n / log n ) {\displaystyle O(n/\log n)} , as expressed using big O notation . [ 3 ]