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Top Forums Shell Programming and Scripting Select Record based on First Column Post 302126937 by Shell_Life on Saturday 14th of July 2007 09:01:37 AM
Old 07-14-2007
Quote:
Originally Posted by matrixmadhan
Why do you need egrep when only a single pattern is specified in the regex ? Smilie
Matrixmadhan,
Thanks for verifying my solution.
You are right about it -- for this specific case, I don't really need 'egrep'.

Matrix, I have a habit of always use 'egrep' no matter what.

This comes from the fact that I have had problems trying to use some full
regular expressions with 'grep' -- I had to specify the '-E' option.

Sometimes I found that out after a long headache.

From my last disaster, I promise myself to never use 'grep' again, always 'egrep'.

Matrix, also to reinforce my idea, all three versions of 'grep' in my system all have the same hardlink:
Code:
>ls -li grep egrep fgrep
329785 -r-xr-xr-x  7 root  bin  22.1K Apr 12 09:11 egrep
329785 -r-xr-xr-x  7 root  bin  22.1K Apr 12 09:11 fgrep
329785 -r-xr-xr-x  7 root  bin  22.1K Apr 12 09:11 grep

Which leads me to believe that they are all the same program.

Hope to have answered your question.

Cheers.Smilie
 

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regcmp(1)                                                          User Commands                                                         regcmp(1)

NAME
regcmp - regular expression compile SYNOPSIS
regcmp [-] filename... DESCRIPTION
The regcmp command performs a function similar to regcmp and, in most cases, precludes the need for calling regcmp from C programs. Bypass- ing regcmp saves on both execution time and program size. The command regcmp compiles the regular expressions in filename and places the output in filename.i. OPTIONS
- If the - option is used, the output is placed in filename.c. The format of entries in filename is a name (C variable) followed by one or more blanks followed by one or more regular expressions enclosed in double quotes. The output of regcmp is C source code. Compiled regular expressions are represented as extern char vectors. filename.i files may thus be #included in C programs, or filename.c files may be compiled and later loaded. In the C program that uses the regcmp output, regex(abc,line) applies the regu- lar expression named abc to line. Diagnostics are self-explanatory. EXAMPLES
Example 1: Examples of the regcmp command. name "([A-Za-z][A-Za-z0-9_]*)$0" telno "({0,1}([2-9][01][1-9])$0){0,1} *" "([2-9][0-9]{2})$1[ -]{0,1}" "([0-9]{4})$2" The three arguments to telno shown above must all be entered on one line. In the C program that uses the regcmp output, regex(telno, line, area, exch, rest) applies the regular expression named telno to line. ENVIRONMENT VARIABLES
A general description of the usage of the LC_* environmental variables can be found in environ(5). LC_CTYPE Determines how regcmp handles characters. When LC_CTYPE is set to a valid value, regcmp can display and handle text and filenames containing valid characters for that locale. LC_MESSAGES Determines how diagnostic and informative messages are presented. This includes the language and style of the messages, and the correct form of affirmative and negative responses. In the "C" locale, the messages are presented in the default form found in the program itself (in most cases, U.S. English). ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWtoo | +-----------------------------+-----------------------------+ |CSI |Enabled | +-----------------------------+-----------------------------+ SEE ALSO
regcmp(3C), attributes(5), environ(5) SunOS 5.10 Dec 20 1996 regcmp(1)
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