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ksh String Manipulation - removing variables from within a variable


 
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# 8  
Old 02-01-2019
Quote:
Originally Posted by MadeInGermany
For example, Solaris ksh88:
Code:
echo "${NAMES//${EXCLUDE_NAME}}"
ksh: "${NAMES//${EXCLUDE_NAME}}": bad substitution

Hmm, in this case i stand corrected. I only used it with the sh version in AIX (which is a ksh88) and there it works. So either it is a bug from porting it to Solaris or IBM fixed it when porting the ksh to AIX. Interesting to know that this feature seems not so global as i thought it to be.

/Addendum: only now i recognised a rather careless typo in my example above, which i have now corrected: instead of the correct ${NAMES/${EXCLUDE_NAME}/} (replace ${EXCLUDE_NAME} with nothing) i used ${NAMES//${EXCLUDE_NAME}} (replace nothing with ${EXCLUDE_NAME} ??), which is fo course wrong. You may want to try again with Solaris as, alas, my trusted old U05 seems not to work any more.

@apmcd74:
Please notice that when you define a variable with:

Code:
cname=( word1 word2 word3 [...] )

you create an array, not a string. The parameter expansion ${cname/searchword/replacement} deals with strings though. i.e.

Code:
variable="++old++"
echo ${variable/old/NEW}
++NEW++

bakunin

Last edited by bakunin; 02-01-2019 at 08:29 AM..
This User Gave Thanks to bakunin For This Post:
# 9  
Old 02-01-2019
Thanks for the reply. Appreciate it.
# 10  
Old 02-01-2019
Quote:
Originally Posted by user052009
Thanks for the reply. Appreciate it.
When you want to give thanks to a member for their help, please click on the "thumbs up" icon in the post(s) you want to thank them.

Everyone here appreciates a bit of thanks for their work.
# 11  
Old 02-01-2019
Quote:
Originally Posted by Neo
When you want to give thanks to a member for their help, please click on the "thumbs up" icon in the post(s) you want to thank them.

Everyone here appreciates a bit of thanks for their work.
Gave a thumbs up as well. Definitely appreciate the feedback and excellent discussion.
This User Gave Thanks to user052009 For This Post:
# 12  
Old 02-01-2019
Quote:
Originally Posted by bakunin
@apmcd74:
Please notice that when you define a variable with:

Code:
cname=( word1 word2 word3 [...] )

you create an array, not a string. The parameter expansion ${cname/searchword/replacement} deals with strings though. i.e.

Code:
variable="++old++"
echo ${variable/old/NEW}
++NEW++

bakunin
My point was that you can do string manipulation per element, or for all elements in an array of strings, thus:
Code:
$ array=( john paul george ringo )
$ echo ${array[0]/h/}
jon
$ for btl in ${array[@]^}
> do
>   echo $btl
> done
John
Paul
George
Ringo
$

As I said, this works for bash and ksh93 on my Ubuntu systems; I haven't tried it out on ksh88.

Andrew
These 2 Users Gave Thanks to apmcd47 For This Post:
# 13  
Old 02-01-2019
Quote:
Originally Posted by bakunin
...
/Addendum: only now i recognised a rather careless typo in my example above, which i have now corrected: instead of the correct ${NAMES/${EXCLUDE_NAME}/} (replace ${EXCLUDE_NAME} with nothing) i used ${NAMES//${EXCLUDE_NAME}} (replace nothing with ${EXCLUDE_NAME} ??), which is fo course wrong. You may want to try again with Solaris as, alas, my trusted old U05 seems not to work any more.
...
I'm happy (or should I be sorry?) to be able to correct your humble self-correction: the original expression was NOT wrong but corresponds to the second form quoted below. man ksh:

Quote:
${parameter/pattern/string}
${parameter//pattern/string}
${parameter/#pattern/string}
${parameter/%pattern/string}

Expands parameter and replaces the longest match of pattern with the specified string. Each occurrence of \n in string is replaced by the portion of parameter that matches the nth sub-pattern.
...
In the first form, only the first occurrence of pattern is replaced.
In the second form, each match for pattern is replaced by the specified string.
This User Gave Thanks to RudiC For This Post:
# 14  
Old 02-01-2019
I pointed out earlier that // means "global". That makes sense because an empty search would not make sense.
Now RudiC opened my eyes for the /# and /% modifiers. Again, makes sense!

OMG bash-4 comes with even more modifiers:
Code:
 array=( john paul george ringo )
 for btl in ${array[@]}; do echo "$btl"; done 
john
paul
george
ringo
 for btl in ${array[@]^}; do echo "$btl"; done
John
Paul
George
Ringo
 for btl in ${array[@]^^}; do echo "$btl"; done
JOHN
PAUL
GEORGE
RINGO


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