Shell Programming and Scripting

How to say "match anything but this or that string" using only posix extended syntax? I am not talking about egrep -v, I want this done entirely by the regular expression. Thanks

you does not use regex or exregex for grep -v emulation if you dont want.

Code:

# cat file2
this is a line
test line is ok!!
what is that ?
test2 line is ok!!!
test2 that and this line is NOTok!!!

Code:

# ./justdoit2 this that file2
test line is ok!!
test2 line is ok!!!

Code:

#!/bin/bash
while read -ra l ; do for i in $1 $2 ; do
br=0;br2=0 ; for j in ${l[@]} ; do
if [ $j = $i ] ; then br=1 ; break ; fi ; done
if [ $br -eq 1 ] ; then br2=1 ; break ; fi ; done
if [ $br2 -eq 0 ] ; then echo "${l[@]}" ; fi ; done<$3

regards
ygemici

You really have not given us enough information to provide a useful answer. Do you want to use the extended regular expression with a shell or with a utility like sed?

With find -regex (with -regextype posix extended) not sed or grep. It is for an auditing script that checks for non-standard filenames.

Right now the user only has the ability to specify the place to start looking and the regex itself, in a bunch of files that lay down the rules for the audit. I would like to avoid using '!' since this would greatly alter the way things are done, but it doesn't look like this is possible.

It doesn't look like posix extended syntax is powerful enough to handle this functionality by itself.

This can be done but it's not pretty:

Code:

$ grep -E '^([^t]|t[^h]|th[^ia]|thi[^s]|tha[^t])*.{0,3}$' file2
test line is ok!!
test2 line is ok!!!

And this is a simplified case as the two words ("this" and "that") are the same length and both start with "th".

@Chubler_XL
stevensw does not want grep..
and your grep statement matches with xxxx(this|that) or (that|this)xxxxx in same time.

@stevensw
how do you think compare strings just by use regex ?
is there any input and desired ouptut ?

regards
ygemici

@ygemici
Grep is just used here to demonstrate the extended regular expression in action. The OP has requested we not use the negation options (! or -v), as these add complexity to the system requiring them.

I can't see any problem with the R.E I supplied; can you supply a string that gives a false positive/negative? Remember this R.E. is supposed to match any line that doesn't contain "this" or "that".