At least you would know the name of the file that contained the string. I don’t know of a grep that has a work-around for this behavior, but you could use the -l option instead, which prints the file name only and not the line containing the string. In the following example, the user is searching for any C files containing “hello.” There is only one C file in the directory, so the output is identical to the previous example. If hello.c were the only file in the current directory, using a wild card to locate the file would still produce an unnamed file output. The one-file rule applies whether you use a wild card in your file list or not. If only one file is named on the command line, the output doesn’t include the file name, as in the following example: The output of grep varies depending on whether you’re searching one or several files. This command searches all files in the current directory and prints the file name and the line containing the string “hello” for any files that contain that string. Intro.txt: use the hello.c program as an example of C programming hello.c: printf(“Hello, world. Story.txt: I could hear my echo, “HELLO.” In the following example, more hellos show up because the search is case independent. y is now considered obsolete, although some versions of grep do support both. Earlier versions of grep used -y, and later versions use -i. Grep is case sensitive, so in order to change the search to include “hello,” “Hello,” or “HELLO,” use the -y or -i option.
Intro.txt: use the hello.c program as an example of C programming Story.txt: so I said hello and she smiled back The output of this command might be something like this: The simplest grep command is grep (search pattern) (files list), as in: The name grep is derived from the editor command g/re/p, which literally translates to “globally search for a regular wxpression and print what you find.” Regular expressions are at the core of grep, and I’ll cover them after a brief description of some of the utility’s command options.
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