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

SearchCompliance
  • OPSEC (operations security)

    OPSEC (operations security) is a security and risk management process and strategy that classifies information, then determines ...

  • smart contract

    A smart contract is a decentralized application that executes business logic in response to events.

  • compliance risk

    Compliance risk is an organization's potential exposure to legal penalties, financial forfeiture and material loss, resulting ...

SearchSecurity
  • buffer overflow

    A buffer overflow occurs when a program or process attempts to write more data to a fixed-length block of memory, or buffer, than...

  • biometric verification

    Biometric verification is any means by which a person can be uniquely identified by evaluating one or more distinguishing ...

  • password

    A password is a string of characters used to verify the identity of a user during the authentication process.

SearchHealthIT
SearchDisasterRecovery
  • What is risk mitigation?

    Risk mitigation is a strategy to prepare for and lessen the effects of threats faced by a business.

  • change control

    Change control is a systematic approach to managing all changes made to a product or system.

  • disaster recovery (DR)

    Disaster recovery (DR) is an organization's ability to respond to and recover from an event that affects business operations.

SearchStorage
  • What is RAID 6?

    RAID 6, also known as double-parity RAID, uses two parity stripes on each disk. It allows for two disk failures within the RAID ...

  • PCIe SSD (PCIe solid-state drive)

    A PCIe SSD (PCIe solid-state drive) is a high-speed expansion card that attaches a computer to its peripherals.

  • VRAM (video RAM)

    VRAM (video RAM) refers to any type of random access memory (RAM) specifically used to store image data for a computer display.

Close