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Full Discussion: Using GNU Regex
Top Forums Shell Programming and Scripting Using GNU Regex Post 302978983 by rthomas529 on Sunday 7th of August 2016 02:44:42 PM
Old 08-07-2016
Using GNU Regex
I'm just learning Regex and while testing my understanding I received some unexpected results.

I created example.txt with the text "abcddd". Running the command
Code:
grep --color '[^abc]d' example.txt

I received the results:
Code:
"abcddd"

with the first and second letter d highlighted in red.


So based on this return my statement meant- search the file example.txt for a string where the first character is not a,b, or c that is followed by the character d and highlight the found characters.

What is confusing is that in my LPIC guide the character ^ represents the start of line. In practice it seems to represent "exclude the following characters". Is there a difference in using it inside the brackets vs. outside brackets?

---------- Post updated at 01:44 PM ---------- Previous update was at 01:25 PM ----------

Apologize I actually found the answer in after reading more carefully.

The use of carat "^a" specifies that the line start with the character "a".
Last edited by vbe; 08-07-2016 at 05:28 PM..
 

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LEARN ABOUT REDHAT

unix2dos

unix2dos(1)						      General Commands Manual						       unix2dos(1)

NAME

       unix2dos - UNIX to DOS text file format converter

SYNOPSYS

       unix2dos [options] [-c convmode] [-o file ...] [-n infile outfile ...]

       Options:

       [-hkqV] [--help] [--keepdate] [--quiet] [--version]

DESCRIPTION

       This manual page documents unix2dos, the program that converts text files in UNIX format to DOS format.

OPTIONS

       The following options are available:

       -h --help
	      Print online help.

       -k --keepdate
	      Keep the date stamp of output file same as input file.

       -q --quiet
	      Quiet mode. Suppress all warning and messages.

       -V --version
	      Prints version information.

       -c --convmode convmode
	      Sets conversion mode. Simulates unix2dos under SunOS.

       -o --oldfile file ...
	      Old file mode. Convert the file and write output to it. The program default to run in this mode. Wildcard names may be used.

       -n --newfile infile outfile ...
	      New  file  mode.	Convert the infile and write output to outfile. File names must be given in pairs and wildcard names should NOT be
	      used or you WILL lost your files.

EXAMPLES

       Get input from stdin and write output to stdout.

	      unix2dos

       Convert and replace a.txt. Convert and replace b.txt.

	      unix2dos a.txt b.txt

	      unix2dos -o a.txt b.txt

       Convert and replace a.txt in ASCII conversion mode.  Convert and replace b.txt in ISO conversion mode.

	      unix2dos a.txt -c iso b.txt

	      unix2dos -c ascii a.txt -c iso b.txt

       Convert and replace a.txt while keeping original date stamp.

	      unix2dos -k a.txt

	      unix2dos -k -o a.txt

       Convert a.txt and write to e.txt.

	      unix2dos -n a.txt e.txt

       Convert a.txt and write to e.txt, keep date stamp of e.txt same as a.txt.

	      unix2dos -k -n a.txt e.txt

       Convert and replace a.txt. Convert b.txt and write to e.txt.

	      unix2dos a.txt -n b.txt e.txt

	      unix2dos -o a.txt -n b.txt e.txt

       Convert c.txt and write to e.txt. Convert and replace a.txt.  Convert and replace b.txt. Convert d.txt and write to f.txt.

	      unix2dos -n c.txt e.txt -o a.txt b.txt -n d.txt f.txt

DIAGNOSTICS

BUGS

       The program does not work properly under MSDOS in stdio processing mode.  If you know why is that so, please tell me.

AUTHOR

       Benjamin Lin - ( blin@socs.uts.edu.au )

MISCELLANY

       Tested environment:

	      Linux 1.2.0 with GNU C 2.5.8

	      SunOS 4.1.3 with GNU C 2.6.3

	      MS-DOS 6.20 with Borland C++ 4.02

       Suggestions and bug reports are welcome.

SEE ALSO

       dos2unix(1)

1995.03.31							   unix2dos v2.2						       unix2dos(1)
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