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ksh using `` or $()

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# 15  
Old 11-12-2010
Code:
[[ !(s)  = kparms.shl ]] && echo ok
[[ !(S)  = kparms.shl ]] && echo ok

! == not the simple regex
*, +, ? also apply.

see: [Chapter 4] 4.3 String Operators
# 16  
Old 11-12-2010
Quote:
Originally Posted by DGPickett
I am lukewarm about overloading = and == for patterns:
Code:
 
           string = pattern    True if string matches pattern.
           string != pattern   True if string does not match pattern.

string = pattern is obsolete within [[ ]]. Correct is: string == pattern.

Quote:
Korn says double quoting turns off pattern recog., same as on the command line. How does one do regex?
Code:
if [[ "a.3.578.yyy" =~ .\.[0-9]\..*y ]]; then
  echo hello
fi

even:
Code:
if [[ a.3.578.yyy =~ .\.[0-9]\..*y ]]; then
  echo hello
fi

Last edited by Scrutinizer; 11-12-2010 at 09:17 PM..
# 17  
Old 11-12-2010
Well, at least that symbol is asymmetrical and not such an overload! I wonder if it works on dtksh on my old HP boxes! Smilie
# 18  
Old 11-12-2010
It might well be. It seems to be in the original ksh93 man page. Let us know if it works...
Last edited by Scrutinizer; 11-13-2010 at 04:34 AM..
# 19  
Old 11-12-2010
Quote:
Quote:
Originally Posted by DGPickett View Post
What is the virtue of [[]] to justify the additional typing?
It is less picky on quoting and spacing, no field splitting and file name generation are performed, there are extra unary and binary expressions, it enables both pattern matching and ERE (regex) matching, plus it is faster.
Edit/Delete Message
Hmm, those attributes have nothing to do with [[...]] as far as I am aware. For example consider the following short ksh93 example which involves pretty sophisticated regex'ing across a newline using the AST REG_NEWLINE and REG_SPAN flags:

Code:
#!/bin/ksh93

string=$'one\nfpm'

for expr in '.fpm/vhc' '^fpm/vhc'
do  for mode in E Es Em Ems
    do  eval 'result=${string/~('$mode')'$expr'}'
        printf $'%-3s %-12s %q\n' "$mode" "$expr" "$result"
    done
done

Here is the expected output:
Code:
E   .fpm/vhc     onevhc
Es  .fpm/vhc     onevhc
Em  .fpm/vhc     $'one\nfpm'
Ems .fpm/vhc     onevhc
E   ^fpm/vhc     $'one\nfpm'
Es  ^fpm/vhc     $'one\nfpm'
Em  ^fpm/vhc     $'one\nvhc'
Ems ^fpm/vhc     $'one\nvhc'

# 20  
Old 11-12-2010
What attributes are you referring to? I was referring to the =~ operator within [[ ]] (as one of the advantages of using [[ ]] instead of [ ] )
Last edited by Scrutinizer; 11-12-2010 at 10:22 PM..
# 21  
Old 11-12-2010
Quote:
It is less picky on quoting and spacing, no field splitting and file name generation are performed, there are extra unary and binary expressions, it enables both pattern matching and ERE (regex) matching, plus it is faster.

ERE (regex) matching for one
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