..."Does not have '=' 0 or more times" is a poor way to describe it; "0 or more characters that aren't a '='", or more simply, "grab characters until you hit a '='" would be more accurate.
Agree!
I has been aplying description automaticaly,
but more precize reading of the [^=]* is:
--- 'not '=' character(s) 0 or more times',
concluding, as you have said:
--- anything, untill '='
I see.
So, if the specified string exist more than once, reg-ex selecting last one!
Hm, not obviouse logic!
But, the solution 'until not =' is not the best. How to do the same if defined search part will be, say, 'BOOBOO'?
I am not a guru in reg-ex.
I know in 'patern removal expantion' that situation could be prevented by syntaxis: ${varnm%boo*} - removes first match from end, ${varnm%%boo*} - removes all, as they said - longest match.
Maybe something like that is available for sed regular exprecions, but I do not know.
Agree!
I has been aplying description automaticaly,
but more precize reading of the [^=]* is:
--- 'not '=' character(s) 0 or more times',
concluding, as you have said:
--- anything, untill '='
I see.
So, if the specified string exist more than once, reg-ex selecting last one!
Hm, not obviouse logic!
But, the solution 'until not =' is not the best. How to do the same if defined search part will be, say, 'BOOBOO'?
I am not a guru in reg-ex.
I know in 'patern removal expantion' that situation could be prevented by syntaxis: ${varnm%boo*} - removes first match from end, ${varnm%%boo*} - removes all, as they said - longest match.
Maybe something like that is available for sed regular exprecions, but I do not know.
Each RegEx, as read left-to-right, consumes as many characters as it can. Given that context, perhaps it now makes more sense?
In Perl, one can append the "?" character to specify a non-greedy match--that is, match only as much as is needed to satisfy the condition. In this case, however, there's a simple answer: give it what it wants:
Code:
env |sed 's/PASS=.*/PASS=*****/' |grep -i pass
Since sed will match the earliest occurrence of "PASS=" it can find in each line, we've now hit paydirt. There are some corner cases here (like "UNRELATEDVARIABLE=None may PASS= this point."), but all can be defeated by including a test:
angry-chipmunk:~$ env | grep PASS
SECRETPASS=n0b0dyc4nevergue55myPASS=word
UNRELATEDVARIABLE=None may PASS= this point
MYPASS=foobar
MYPASSWORD=foobar
angry-chipmunk:~$ env|sed '/^[^=]*PASS=/ {s/PASS=.*/PASS=*****/}' |grep -i pass
SECRETPASS=*****
UNRELATEDVARIABLE=None may PASS= this point
MYPASS=*****
MYPASSWORD=foobar
Thank you BMDan for explanation.
I remember you have mention about some other potentional problem with that statement. I do not see anythink. Did you changed your mind about that or just have no time and interest to show that?
Hi All,
I need to understand following three environment variables and their usages in HP Unix.
_M_ARENA_OPTS
_M_CACHE_OPTS
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Read Unix The textbook.
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Hello Everyone
I need to create a script file which must append some lines to a target text file, I'm using sed for windows, the script file look like this:
{
a\
STRINGTABLE DISCARDABLE\
BEGIN\
5, 150 {a\
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using sed to replace a specific string on a specific line number using variables
this is where i am at
grep -v WARNING output | grep -v spawn | grep -v Passphrase | grep -v Authentication | grep -v '/sbin/tfadmin netguard -C'| grep -v 'NETWORK>' >> output.clean
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hi,
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Hi!
How-to get the environment variables in GNU.
getenv() only fetches the ones that you can find under export (not the ones under declare)...
best regars .David (2 Replies)
