Browse Definitions :
Definition

grep

Grep, a UNIX command and also a utility available for Windows and other operating systems, is used to search one or more files for a given character string or pattern and, if desired, replace the character string with another one. For example, a UNIX system user can enter on a command line:

grep html homepage.htm

html specifies the character string to search for on each line. homepage.htm specifies the file to search. The result would be to display any line in the homepage.htm file that includes the character string html. The entire line is displayed.

grep can be used simply as a way of searching, especially through multiple files. (In the above command, we could have specified additional files besides homepage.htm.) It can also be used to search for word or string occurrences that need to be replaced. If you are not sure exactly what the effect might be of making the replacement, grep identifies the lines and you can decide what further action to take for each occurrence. grep can also be used as the first step in an automatic procedure to search and replace a word or phrase. The output from grep can be the input (perhaps using the UNIX pipe symbol) for a replacement command.

grep allows the string argument to be specified as a regular expression, which is a way of specifying a string that allows certain metacharacters (special keyboard characters such as the period) to stand for other characters or to further define the way the pattern-matching should work. For example:

grep ".*hood" essay1

would search the essay1 file and display every line containing a word with the string hood. The period (dot) indicates that any character may precede the string hood and the asterisk (*) says that any number of the "any characters" indicated by the dot can precede the string. (The quote marks around the string argument in this example are optional, but quotes are required where the argument is a phrase or contains a blank.)

grep originated from a UNIX text editor that provided a command sequence g/re/p for global/regular expression/print.

This was last updated in September 2005

Continue Reading About grep

SearchNetworking
  • virtual network functions (VNFs)

    Virtual network functions (VNFs) are virtualized tasks formerly carried out by proprietary, dedicated hardware.

  • network functions virtualization (NFV)

    Network functions virtualization (NFV) is a network architecture model designed to virtualize network services that have ...

  • overlay network

    An overlay network is a virtual or logical network that is created on top of an existing physical network.

SearchSecurity
  • encryption

    Encryption is the method by which information is converted into secret code that hides the information's true meaning.

  • X.509 certificate

    An X.509 certificate is a digital certificate that uses the widely accepted international X.509 public key infrastructure (PKI) ...

  • directory traversal

    Directory traversal is a type of HTTP exploit in which a hacker uses the software on a web server to access data in a directory ...

SearchCIO
  • resource allocation

    Resource allocation is the process of assigning and managing assets in a manner that supports an organization's strategic ...

  • chief digital officer (CDO)

    A chief digital officer (CDO) is charged with helping an enterprise use digital information and advanced technologies to create ...

  • security audit

    A security audit is a systematic evaluation of the security of a company's information system by measuring how well it conforms ...

SearchHRSoftware
SearchCustomerExperience
  • implementation

    Implementation is the execution or practice of a plan, a method or any design, idea, model, specification, standard or policy for...

  • first call resolution (FCR)

    First call resolution (FCR) is when customer service agents properly address a customer's needs the first time they call.

  • customer intelligence (CI)

    Customer intelligence (CI) is the process of collecting and analyzing detailed customer data from internal and external sources ...

Close