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tools:grep [2024/09/28 02:55] – [Variations] Humphrey Boa-Garttools:grep [2025/09/30 22:44] (current) – external edit 127.0.0.1
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 ====== grep ====== ====== grep ======
  
-**grep** is a command line text search utility originally written for Unix. The name is taken from a command for the ancient UNIX text editor **ed** - ''g/re/p'' //(global regular expression search and print)// which has the same effect. The grep command searches files or standard input globally for lines matching a given regular expression, and prints them to the program's standard output. It is one of the most essential commands you will need to use in [[tools:bash|Linux command line]].+**grep** is a command line text search utility originally written for Unix. The name is taken from a command for the ancient UNIX text editor **ed** - ''g/re/p'' //(global regular expression search and print)// which has the same effect. The ''grep'' command searches files or standard input globally for lines matching a given regular expression, and prints them to the program's standard output. It is one of the most essential commands you will need to use in [[tools:bash|Linux command line]].
  
-If you are using a modern version of Linux, chances are that grep is already installed on your system. If not, it is probably in your distro's official repositories. Consult your [[tools:package-manager|Package Manager]] for more information.+If you are using a modern version of Linux, chances are that ''grep'' is already installed on your system. If not, it is probably in your distro's official repositories. Consult your [[tools:package-manager|Package Manager]] for more information.
  
  
 ===== Useful Commands ===== ===== Useful Commands =====
  
-Using grep may seem obtuse to new users at first. However, once you know how to structure your commands, it is the absolute fastest way to do many common searches:+Using ''grep'' may seem obtuse to new users at first. However, once you know how to structure your commands, it is the absolute fastest way to do many common searches:
  
 ==== Built-in Documentation ==== ==== Built-in Documentation ====
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 ==== Search Files in Current Directory ==== ==== Search Files in Current Directory ====
  
-You can also use grep to search inside all the files within a folder, and not just one. Just replace the filename with an asterisk. To search the PWD for all files containing //INSERTSTRING//, format your command as so:+You can also use ''grep'' to search inside all the files within a folder, and not just one. Just replace the filename with an asterisk. To search the pwd for all files containing //INSERTSTRING//, format your command as so:
  
   $ grep “INSERTSTRING” *   $ grep “INSERTSTRING” *
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   $ grep “INSERT*” *.txt   $ grep “INSERT*” *.txt
  
-The ''-R'' flag lets you search child directories. So to search your PWD **and** all child directories recursively for all files containing //INSERTSTRING//:+The ''-R'' flag lets you search child directories. So to search your pwd **and** all child directories recursively for all files containing //INSERTSTRING//:
  
   $ grep -R "INSERTSTRING" *   $ grep -R "INSERTSTRING" *
  
-You can combine flags as well. To search your PWD and all child directories recursively for all //.txt// files containing //INSERTSTRING//, and to make grep tell you the line number that the string is found on, combine the ''-R'' and ''-n'' flags like this:+You can combine flags as well. To search your pwd and all child directories recursively for all //.txt// files containing //INSERTSTRING//, and to make grep tell you the line number that the string is found on, combine the ''-R'' and ''-n'' flags like this:
  
   $ grep -Rn "INSERTSTRING" *.txt   $ grep -Rn "INSERTSTRING" *.txt
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 +==== More Command Flags ====
 +
 +There are more flags you can combine with these basic ''grep'' commands to fine-tune your search. Play around with them to see how they affect output!
 +
 +  * ''-i'' - Searches made with ''grep'' are case-sensitive. Use this flag to search for both uppercase and lowercase versions of the same string.
 +  * ''-l'' - Print only the filename(s) of search results. Incredibly useful when using ''-R'' on large directory trees.
 +  * ''-w'' - Match only whole words.
 +  * ''-x'' - Match only whole lines.
 +  * ''-v'' - Inverted search. Returns only non-matching lines.
 +  * ''-s'' - Suppress error messages. Useful in bash scripts.
 ===== Variations ===== ===== Variations =====
  
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