Difference Between grep and egrep
- Definition. The grep is a command-line utility for searching plain-text data sets for lines that match a regular expression.
- Representation. Grep represents Global Regular Expressions Print whereas egrep represents Extended Global Regular Expressions Print.
- Usage. The grep uses regular expressions for searching. ...
- Meta Characters. ...
- Conclusion. ...
Full Answer
Is Perl faster than egrep?
The regex engine in Perl is much faster than the regex engine of Python. The are both slower than grep as measured when I compares Python with grep.
What does egrep stand for?
egrep is an acronym for "Extended Global Regular Expressions Print". It is a program which scans a specified file line by line, returning lines that contain a pattern matching a given regular expression. What's Difference Between Grep, Egrep and Fgrep in Linux?
What is the difference between SED and grep?
grep: find stuff in one or more files very quickly. It has provisions for finding things before or after the given line, case sensitivity, regular expressions, binary files, and colorizing. sed - a stream editor. in a sequential fashion, go through a file and replace X with Y.
What does grep stand for?
GREP: Generalization of the Richardson Extrapolation Process: GREP: Get Regular Expression and Print: GREP: General Regular Expression Processor: GREP: Globally for Regular Expression Print: GREP: Global Regular Expression Pattern: GREP: Genetic Resources and Enhancement Program: GREP: Gas Rehabilitation and Expansion Project: GREP: Gambian ...
What is grep egrep?
The egrep command is shortcut for grep binary, but with one exception, when grep is invoked as egrep the grep binary activates its internal logic as it would be called as grep -E.
What does grep mean without a back slash?
However, for |, grep, without back slash in front of |, means character of |, and if I put a back slash in front of it, it turns on it special meaning of finding the line contains either the stuff in front of it and behind it. BUT, for egrep, it is the opposite. | has the latter meanings of grep and | has the former meaning of grep when uses it.
Is grep the same as egrep?
The variant program egrep is the same as grep -E. The variant is deprecated, but is provided for backward compatibility.
Is egrep a regular expression?
egrep is equal to grep -E,which is extended regular expression uses {,}, (,),|,? as meta-characters without giving '' in expression
What is grep command?
Grep is an amazing utility on command line. Every one might have heard of grep. It's a great tool to search for a pattern with in a directory or in a file. On searching for a pattern using grep, the default result will print the pattern along with the line number at which the pattern is found. Grep is one of those handy commands on bash ...
Is grep the same as egrep?
I have played around with grep for a while, at some point I have noticed egrep. grep and egrep does the same function, but the way they interpret the pattern is the only difference.
What is grep e?
Egrep or grep -E is another version of grep or the Extended grep. This version of grep is efficient and fast when it comes to searching for a regular expression pattern as it treats meta-characters as is and doesn’t substitute them as strings like in grep, and hence you are freed from the burden of escaping them as in grep. It uses ERE or the Extended Regular Expression set.
What is grep command?
grep or Global Regular Expression Print is the main search program on Unix-like systems which can search for any type of string on any file or list of files or even output of any command. It uses Basic Regular Expressions apart from normal strings as a search pattern.
What is a fixed grep?
Fgrep or the Fixed grep or grep -F is yet another version of grep which is fast in searching when it comes to search for the entire string instead of regular expression as it doesn’t recognize the regular expressions, neither any meta-characters. For searching any direct string, this is the version of grep which should be selected.
What algorithm does GREp use?
Also, grep uses Boyer-Moore algorithm for fast searching any string or regular expression.
When does egrep search for file?
Like here, egrep searched for “file” string when the meta-characters were not escaped as it would mean by the meaning of these characters. But, when these characters were escaped, then egrep treated them as part of string and searched for complete string “ (f|g)ile” in the file.
Does Fgrep recognize special characters?
Fgrep searches for complete string and doesn’t even recognize special characters as part of regular expression even if escaped or not escaped.
What does egrep stand for?
The e in egrep stands for extended and the f in fgrep stands for fixed. egrep allows the use of extended regex and fgrep doesn't allow regex at all.
Why should I avoid grep and fgrep?
As I mentioned earlier, you should avoid using egrep and fgrep because they are deprecated commands. Using grep -E and grep -F is the way forward.
Why was Egrep created?
Egrep was created to provide extended support for meta-characters. This means that it escapes these special characters by default. This saves time and generally makes the expressions easier to read.
What are the flags for grep?
However, it is now the POSIX standard to use standard grep with special option flags ( -E or -F ). These flags help standard grep emulate the functionality of each respective command.
Does grep work on regex?
You know that grep works on regex. But that's not the complete truth. By default, the grep command works on basic regular expression. If you want more complex search, you need to use extended regular expression. See the difference between basic and extended regex. The egrep command allows the use of extended regex.
Is grep a tool?
Software professionals know that even as computational capability has increased profoundly, optimization can never be ignored. Grep is a very powerful tool, but it can sometimes use system resources unnecessarily. This is where the idea of fixed grep came from.
Is egrep a deprecated command?
egrep and fgrep are deprecated commands and should be avoided. egrep is equivalent to grep -E command and it allows the use of extended regex. fgrep is equivalent to grep -F command and it uses a fixed string for search and hence it performs a faster search.
What does egrep mean in Linux?
egrep is an acronym for “ Extended Global Regular Expressions Print “. It is a program which scans a specified file line by line, returning lines that contain a pattern matching a given regular expression.
How does grep work in Linux?
Grep is a Linux / Unix command -line tool used to search for a string of characters in a specified file. The text search pattern is called a regular expression. When it finds a match, it prints the line with the result. The grep command is handy when searching through large log files.
Does grep support regex?
A regular expression or regex is a pattern that matches a set of strings. … GNU grep supports three regular expression syntaxes, Basic, Extended, and Perl-compatible. In its simplest form, when no regular expression type is given, grep interpret search patterns as basic regular expressions.
What options can be used with grep command?
The grep command supports a number of options for additional controls on the matching:
Should I use grep or egrep?
grep and egrep does the same function, but the way they interpret the pattern is the only difference. Grep stands for “Global Regular Expressions Print”, were as Egrep for “Extended Global Regular Expressions Print”. … The grep command will check whether there is any file with .
