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Top Forums Shell Programming and Scripting grep with "[" and "]" and "dot" within the search string Post 302712345 by bakunin on Tuesday 9th of October 2012 05:32:42 AM
Old 10-09-2012
Quote:
Originally Posted by jethro10
does fgrep works? i tried it once...
"fgrep" is a faster variant of "grep". It uses simplified regular expressions, but this speeds up its performance considerably. For small files this will make no big difference but with large files it can save a lot of time. On the other hand "fgrep" is not as versatile as "grep", so there indeed are cases where "grep" will do the job but "fgrep" won't.

As a general rule: use "fgrep" when you can and "grep" when you must.

Corollary: the same goes for "grep" and "egrep" - at least where they are different. "egrep" can do even more than "grep", but again at the expense of speed. Its operation is even slower than that of "grep". In some systems, though, one is just a hard link to the other because the makers saved some time and effort in silently merging these two tools.

I hope this helps.

bakunin
 

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cd(1)							      General Commands Manual							     cd(1)

NAME
cd - change working directory SYNOPSIS
[directory] DESCRIPTION
If directory is not specified, the value of shell parameter is used as the new working directory. If directory specifies a complete path starting with or directory becomes the new working directory. If neither case applies, tries to find the designated directory relative to one of the paths specified by the shell variable. has the same syntax as, and similar semantics to, the shell variable. must have execute (search) permission in directory. exists only as a shell built-in command because a new process is created whenever a command is executed, making useless if written and pro- cessed as a normal system command. Moreover, different shells provide different implementations of as a built-in utility. Features of as described here may not be supported by all the shells. Refer to individual shell manual entries for differences. If is called in a subshell or a separate utility execution environment such as: (which invokes on accessible directories) does not affect the current directory of the caller's environment. Another usage of as a stand- alone command is to obtain the exit status of the command. EXTERNAL INFLUENCES
International Code Set Support Single- and multi-byte character code sets are supported. Environment Variables The following environment variables affect the execution of The name of the home directory, used when no directory operand is specified. A colon-separated list of pathnames that refer to directories. If the directory operand does not begin with a slash character, and the first component is not dot or dot-dot, searches for directory relative to each directory named in the variable, in the order listed. The new working directory is set to the first matching directory found. An empty string in place of a directory pathname represents the current direc- tory. If is not set, it is treated as if it was an empty string. EXAMPLES
Change the current working directory to the directory from any location in the file system: Change to new current working directory residing in the current directory: or Change to directory residing in the current directory's parent directory: Change to the directory whose absolute pathname is Change to the directory relative to home directory: RETURN VALUE
Upon completion, exits with one of the following values: The directory was successfully changed. An error occurred. The working directory remains unchanged. SEE ALSO
csh(1), pwd(1), ksh(1), sh-posix(1), sh(1), chdir(2). STANDARDS CONFORMANCE
cd(1)
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