What are some PRACTICAL scenarios for using the regex + symbol?
Clash Royale CLAN TAG#URR8PPP
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So, I think I know what the RegEx + symbol does (looks for the preceding character 1 or more times). I think I get how to use it...
echo "This is a good sentence." | awk '/go+d/ print $0'
(finds good, gooood, gooooooood)
But, I'm having trouble coming up with a practical, objective reason for wanting to look for this kind of repetition. I need scenarios to give its purpose some context for explanation to others.
Thanks for helping and letting me lean on your knowledge and experiences.
regular-expression
asked Oct 10 '17 at 2:09
dlowrie290
8410
add a comment |Â
up vote
0
down vote
favorite
So, I think I know what the RegEx + symbol does (looks for the preceding character 1 or more times). I think I get how to use it...
echo "This is a good sentence." | awk '/go+d/ print $0'
(finds good, gooood, gooooooood)
But, I'm having trouble coming up with a practical, objective reason for wanting to look for this kind of repetition. I need scenarios to give its purpose some context for explanation to others.
Thanks for helping and letting me lean on your knowledge and experiences.
regular-expression
asked Oct 10 '17 at 2:09
dlowrie290
8410
It makes more sense with digits, as I see it...
– jasonwryan
Oct 10 '17 at 2:14
I thought that too, but I couldn't think of a scenario to explain how that would look.
– dlowrie290
Oct 10 '17 at 2:22
1
What about when you want to slurp up whitespace? At least one space, for example.s+. Think about character classes rather than individual characters.
– B Layer
Oct 10 '17 at 2:28
That is EXACTLY the kind of thing I'm looking for. A great example of why you would use this type of functionality.
– dlowrie290
Oct 10 '17 at 2:33
add a comment |Â
up vote
0
down vote
favorite
up vote
0
down vote
favorite
So, I think I know what the RegEx + symbol does (looks for the preceding character 1 or more times). I think I get how to use it...
echo "This is a good sentence." | awk '/go+d/ print $0'
(finds good, gooood, gooooooood)
But, I'm having trouble coming up with a practical, objective reason for wanting to look for this kind of repetition. I need scenarios to give its purpose some context for explanation to others.
Thanks for helping and letting me lean on your knowledge and experiences.
regular-expression
asked Oct 10 '17 at 2:09
dlowrie290
8410
So, I think I know what the RegEx + symbol does (looks for the preceding character 1 or more times). I think I get how to use it...
echo "This is a good sentence." | awk '/go+d/ print $0'
(finds good, gooood, gooooooood)
But, I'm having trouble coming up with a practical, objective reason for wanting to look for this kind of repetition. I need scenarios to give its purpose some context for explanation to others.
Thanks for helping and letting me lean on your knowledge and experiences.
regular-expression
regular-expression
asked Oct 10 '17 at 2:09
dlowrie290
8410
asked Oct 10 '17 at 2:09
dlowrie290
8410
asked Oct 10 '17 at 2:09
dlowrie290
8410
asked Oct 10 '17 at 2:09
dlowrie290
8410
asked Oct 10 '17 at 2:09
dlowrie290
8410
8410
It makes more sense with digits, as I see it...
– jasonwryan
Oct 10 '17 at 2:14
I thought that too, but I couldn't think of a scenario to explain how that would look.
– dlowrie290
Oct 10 '17 at 2:22
1
What about when you want to slurp up whitespace? At least one space, for example.s+. Think about character classes rather than individual characters.
– B Layer
Oct 10 '17 at 2:28
That is EXACTLY the kind of thing I'm looking for. A great example of why you would use this type of functionality.
– dlowrie290
Oct 10 '17 at 2:33
add a comment |Â
It makes more sense with digits, as I see it...
– jasonwryan
Oct 10 '17 at 2:14
I thought that too, but I couldn't think of a scenario to explain how that would look.
– dlowrie290
Oct 10 '17 at 2:22
1
What about when you want to slurp up whitespace? At least one space, for example.s+. Think about character classes rather than individual characters.
– B Layer
Oct 10 '17 at 2:28
That is EXACTLY the kind of thing I'm looking for. A great example of why you would use this type of functionality.
– dlowrie290
Oct 10 '17 at 2:33
It makes more sense with digits, as I see it...
– jasonwryan
Oct 10 '17 at 2:14
It makes more sense with digits, as I see it...
– jasonwryan
Oct 10 '17 at 2:14
I thought that too, but I couldn't think of a scenario to explain how that would look.
– dlowrie290
Oct 10 '17 at 2:22
I thought that too, but I couldn't think of a scenario to explain how that would look.
– dlowrie290
Oct 10 '17 at 2:22
1
1
What about when you want to slurp up whitespace? At least one space, for example.
s+. Think about character classes rather than individual characters.– B Layer
Oct 10 '17 at 2:28
What about when you want to slurp up whitespace? At least one space, for example.
s+. Think about character classes rather than individual characters.– B Layer
Oct 10 '17 at 2:28
That is EXACTLY the kind of thing I'm looking for. A great example of why you would use this type of functionality.
– dlowrie290
Oct 10 '17 at 2:33
That is EXACTLY the kind of thing I'm looking for. A great example of why you would use this type of functionality.
– dlowrie290
Oct 10 '17 at 2:33
add a comment |Â
2 Answers
2
active
oldest
votes
up vote
4
down vote
accepted
You're thinking about individual characters when you'll find that + is much more useful with character classes...
- Whitespace:
s+ - Non-numerical characters:
[^0-9]+ - A word:
w+ - Non-empty string:
.+ - Etc.
Practical examples should be fairly easy to think of with these. Perhaps I want to find only lines that have indented text: ^s+S. Or I might want to find all non-empty lines: ^.+$. I can come up with more if you need them. ;)
answered Oct 10 '17 at 2:42
B Layer
3,9241525
No,[0-9]is numerical.[^0-9]is NOT numerical.
– B Layer
Oct 10 '17 at 2:44
My bad, I read it as^[...
– jasonwryan
Oct 10 '17 at 2:45
No worries. I suspected that that's what you saw. :)
– B Layer
Oct 10 '17 at 2:45
add a comment |Â
up vote
3
down vote
Here's a real-world instance of damage caused by using * instead of + (mostly because OP didn't realise that they would end up using regexes instead of wildcards): Why did this command delete every package?
Arguments to
apt-get installandapt-get removeare extended
regular expressions, not shell
wildcards;
wine*meanswinfollowed by any number ofe, and since this can
match any part of the package name, this means any package whose name
containswinas a substring.
OP had run sudo apt-get remove wine*, ended up removing the majority of the installed packages in their system. wine+, on the other hand, would have removed packages with wine in it.
answered Oct 10 '17 at 2:44
muru
33.6k577144
add a comment |Â
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
4
down vote
accepted
You're thinking about individual characters when you'll find that + is much more useful with character classes...
- Whitespace:
s+ - Non-numerical characters:
[^0-9]+ - A word:
w+ - Non-empty string:
.+ - Etc.
Practical examples should be fairly easy to think of with these. Perhaps I want to find only lines that have indented text: ^s+S. Or I might want to find all non-empty lines: ^.+$. I can come up with more if you need them. ;)
answered Oct 10 '17 at 2:42
B Layer
3,9241525
No,[0-9]is numerical.[^0-9]is NOT numerical.
– B Layer
Oct 10 '17 at 2:44
My bad, I read it as^[...
– jasonwryan
Oct 10 '17 at 2:45
No worries. I suspected that that's what you saw. :)
– B Layer
Oct 10 '17 at 2:45
add a comment |Â
up vote
4
down vote
accepted
You're thinking about individual characters when you'll find that + is much more useful with character classes...
- Whitespace:
s+ - Non-numerical characters:
[^0-9]+ - A word:
w+ - Non-empty string:
.+ - Etc.
Practical examples should be fairly easy to think of with these. Perhaps I want to find only lines that have indented text: ^s+S. Or I might want to find all non-empty lines: ^.+$. I can come up with more if you need them. ;)
answered Oct 10 '17 at 2:42
B Layer
3,9241525
No,[0-9]is numerical.[^0-9]is NOT numerical.
– B Layer
Oct 10 '17 at 2:44
My bad, I read it as^[...
– jasonwryan
Oct 10 '17 at 2:45
No worries. I suspected that that's what you saw. :)
– B Layer
Oct 10 '17 at 2:45
add a comment |Â
up vote
4
down vote
accepted
up vote
4
down vote
accepted
You're thinking about individual characters when you'll find that + is much more useful with character classes...
- Whitespace:
s+ - Non-numerical characters:
[^0-9]+ - A word:
w+ - Non-empty string:
.+ - Etc.
Practical examples should be fairly easy to think of with these. Perhaps I want to find only lines that have indented text: ^s+S. Or I might want to find all non-empty lines: ^.+$. I can come up with more if you need them. ;)
answered Oct 10 '17 at 2:42
B Layer
3,9241525
You're thinking about individual characters when you'll find that + is much more useful with character classes...
- Whitespace:
s+ - Non-numerical characters:
[^0-9]+ - A word:
w+ - Non-empty string:
.+ - Etc.
Practical examples should be fairly easy to think of with these. Perhaps I want to find only lines that have indented text: ^s+S. Or I might want to find all non-empty lines: ^.+$. I can come up with more if you need them. ;)
answered Oct 10 '17 at 2:42
B Layer
3,9241525
edited Oct 10 '17 at 3:29
answered Oct 10 '17 at 2:42
B Layer
3,9241525
answered Oct 10 '17 at 2:42
B Layer
3,9241525
answered Oct 10 '17 at 2:42
B Layer
3,9241525
3,9241525
No,[0-9]is numerical.[^0-9]is NOT numerical.
– B Layer
Oct 10 '17 at 2:44
My bad, I read it as^[...
– jasonwryan
Oct 10 '17 at 2:45
No worries. I suspected that that's what you saw. :)
– B Layer
Oct 10 '17 at 2:45
add a comment |Â
No,[0-9]is numerical.[^0-9]is NOT numerical.
– B Layer
Oct 10 '17 at 2:44
My bad, I read it as^[...
– jasonwryan
Oct 10 '17 at 2:45
No worries. I suspected that that's what you saw. :)
– B Layer
Oct 10 '17 at 2:45
No,
[0-9] is numerical. [^0-9] is NOT numerical.– B Layer
Oct 10 '17 at 2:44
No,
[0-9] is numerical. [^0-9] is NOT numerical.– B Layer
Oct 10 '17 at 2:44
My bad, I read it as
^[...– jasonwryan
Oct 10 '17 at 2:45
My bad, I read it as
^[...– jasonwryan
Oct 10 '17 at 2:45
No worries. I suspected that that's what you saw. :)
– B Layer
Oct 10 '17 at 2:45
No worries. I suspected that that's what you saw. :)
– B Layer
Oct 10 '17 at 2:45
add a comment |Â
up vote
3
down vote
Here's a real-world instance of damage caused by using * instead of + (mostly because OP didn't realise that they would end up using regexes instead of wildcards): Why did this command delete every package?
Arguments to
apt-get installandapt-get removeare extended
regular expressions, not shell
wildcards;
wine*meanswinfollowed by any number ofe, and since this can
match any part of the package name, this means any package whose name
containswinas a substring.
OP had run sudo apt-get remove wine*, ended up removing the majority of the installed packages in their system. wine+, on the other hand, would have removed packages with wine in it.
answered Oct 10 '17 at 2:44
muru
33.6k577144
add a comment |Â
up vote
3
down vote
Here's a real-world instance of damage caused by using * instead of + (mostly because OP didn't realise that they would end up using regexes instead of wildcards): Why did this command delete every package?
Arguments to
apt-get installandapt-get removeare extended
regular expressions, not shell
wildcards;
wine*meanswinfollowed by any number ofe, and since this can
match any part of the package name, this means any package whose name
containswinas a substring.
OP had run sudo apt-get remove wine*, ended up removing the majority of the installed packages in their system. wine+, on the other hand, would have removed packages with wine in it.
answered Oct 10 '17 at 2:44
muru
33.6k577144
add a comment |Â
up vote
3
down vote
up vote
3
down vote
Here's a real-world instance of damage caused by using * instead of + (mostly because OP didn't realise that they would end up using regexes instead of wildcards): Why did this command delete every package?
Arguments to
apt-get installandapt-get removeare extended
regular expressions, not shell
wildcards;
wine*meanswinfollowed by any number ofe, and since this can
match any part of the package name, this means any package whose name
containswinas a substring.
OP had run sudo apt-get remove wine*, ended up removing the majority of the installed packages in their system. wine+, on the other hand, would have removed packages with wine in it.
answered Oct 10 '17 at 2:44
muru
33.6k577144
Here's a real-world instance of damage caused by using * instead of + (mostly because OP didn't realise that they would end up using regexes instead of wildcards): Why did this command delete every package?
Arguments to
apt-get installandapt-get removeare extended
regular expressions, not shell
wildcards;
wine*meanswinfollowed by any number ofe, and since this can
match any part of the package name, this means any package whose name
containswinas a substring.
OP had run sudo apt-get remove wine*, ended up removing the majority of the installed packages in their system. wine+, on the other hand, would have removed packages with wine in it.
answered Oct 10 '17 at 2:44
muru
33.6k577144
answered Oct 10 '17 at 2:44
muru
33.6k577144
answered Oct 10 '17 at 2:44
muru
33.6k577144
answered Oct 10 '17 at 2:44
muru
33.6k577144
33.6k577144
add a comment |Â
add a comment |Â
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It makes more sense with digits, as I see it...
– jasonwryan
Oct 10 '17 at 2:14
I thought that too, but I couldn't think of a scenario to explain how that would look.
– dlowrie290
Oct 10 '17 at 2:22
1
What about when you want to slurp up whitespace? At least one space, for example.
s+. Think about character classes rather than individual characters.– B Layer
Oct 10 '17 at 2:28
That is EXACTLY the kind of thing I'm looking for. A great example of why you would use this type of functionality.
– dlowrie290
Oct 10 '17 at 2:33