grep regexp [A-Z] returns digits
Clash Royale CLAN TAG#URR8PPP
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0
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I have file a.txt with its content as
1 (C##2)
2 (C##U)
and using grep on it
cat a.txt | grep '##[A-Z]*'
1 (C##2)
2 (C##U)
Why did number 1 (C##2) appear in this grep result? I wanted only second one to
appear. So I have specified [A-Z]. Why did it take ..##2 as match?
grep
edited Nov 20 at 5:42
Inian
3,785824
asked Nov 20 at 5:34
mandrake00
294
add a comment |
up vote
0
down vote
favorite
I have file a.txt with its content as
1 (C##2)
2 (C##U)
and using grep on it
cat a.txt | grep '##[A-Z]*'
1 (C##2)
2 (C##U)
Why did number 1 (C##2) appear in this grep result? I wanted only second one to
appear. So I have specified [A-Z]. Why did it take ..##2 as match?
grep
edited Nov 20 at 5:42
Inian
3,785824
asked Nov 20 at 5:34
mandrake00
294
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
I have file a.txt with its content as
1 (C##2)
2 (C##U)
and using grep on it
cat a.txt | grep '##[A-Z]*'
1 (C##2)
2 (C##U)
Why did number 1 (C##2) appear in this grep result? I wanted only second one to
appear. So I have specified [A-Z]. Why did it take ..##2 as match?
grep
edited Nov 20 at 5:42
Inian
3,785824
asked Nov 20 at 5:34
mandrake00
294
I have file a.txt with its content as
1 (C##2)
2 (C##U)
and using grep on it
cat a.txt | grep '##[A-Z]*'
1 (C##2)
2 (C##U)
Why did number 1 (C##2) appear in this grep result? I wanted only second one to
appear. So I have specified [A-Z]. Why did it take ..##2 as match?
grep
grep
edited Nov 20 at 5:42
Inian
3,785824
asked Nov 20 at 5:34
mandrake00
294
edited Nov 20 at 5:42
Inian
3,785824
asked Nov 20 at 5:34
mandrake00
294
edited Nov 20 at 5:42
Inian
3,785824
edited Nov 20 at 5:42
Inian
3,785824
edited Nov 20 at 5:42
Inian
3,785824
3,785824
asked Nov 20 at 5:34
mandrake00
294
asked Nov 20 at 5:34
mandrake00
294
asked Nov 20 at 5:34
mandrake00
294
294
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
up vote
5
down vote
[A-Z]* is zero or more occurrences of [A-Z]. There are zero occurrences of [A-Z] in ##2, so the line matches. You probably want one or more (1, (or + with GNU grep or compatible), or + with the -E option enabling EREs), or simply ##[A-Z] as if it matches ##[A-Z], it also matches ##[A-Z]+ and vice-versa.
Also note that except in the C/POSIX locale, what is matched by [A-Z] is unspecified and the list of characters (or even possibly collation elements made of several characters) it matches varies with the locale and operating system. On GNU systems, it's generally only characters of the Latin script (including things like Dž or É) often only uppercase ones, but sometimes also lowercase ones including the English a-z letters (like in the Thai locale for Thailand on Ubuntu 18.04 at least). You get much more exotic lists in some non-GNU systems like Solaris. To match on ABCDEFGHIJKLMNOPQRSTUVWXYZ only, use [ABCDEFGHIJKLMNOPQRSTUVWXYZ].
edited Nov 20 at 6:14
Stéphane Chazelas
294k54555898
answered Nov 20 at 5:43
muru
35.1k581154
Thank you. ...grep '#[A-Z]+' works. But still amused by "Zero or more matches"... Is it helpful anywhere(any example)? searching for "zero matches" is same as not searching for it at all, isn't it?
– mandrake00
Nov 20 at 5:49
1
At the start or end of a regex, it isn't that useful, but in between, sure. Saya[a-zA-Z]*_.. a string that begins withaand has an underscore somewhere in it, but arbitrary alphabets in between.
– muru
Nov 20 at 5:54
1
@mandrake00 do read Stéphane Chazelas's edit on the answer as well.
– muru
Nov 20 at 6:14
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
5
down vote
[A-Z]* is zero or more occurrences of [A-Z]. There are zero occurrences of [A-Z] in ##2, so the line matches. You probably want one or more (1, (or + with GNU grep or compatible), or + with the -E option enabling EREs), or simply ##[A-Z] as if it matches ##[A-Z], it also matches ##[A-Z]+ and vice-versa.
Also note that except in the C/POSIX locale, what is matched by [A-Z] is unspecified and the list of characters (or even possibly collation elements made of several characters) it matches varies with the locale and operating system. On GNU systems, it's generally only characters of the Latin script (including things like Dž or É) often only uppercase ones, but sometimes also lowercase ones including the English a-z letters (like in the Thai locale for Thailand on Ubuntu 18.04 at least). You get much more exotic lists in some non-GNU systems like Solaris. To match on ABCDEFGHIJKLMNOPQRSTUVWXYZ only, use [ABCDEFGHIJKLMNOPQRSTUVWXYZ].
edited Nov 20 at 6:14
Stéphane Chazelas
294k54555898
answered Nov 20 at 5:43
muru
35.1k581154
Thank you. ...grep '#[A-Z]+' works. But still amused by "Zero or more matches"... Is it helpful anywhere(any example)? searching for "zero matches" is same as not searching for it at all, isn't it?
– mandrake00
Nov 20 at 5:49
1
At the start or end of a regex, it isn't that useful, but in between, sure. Saya[a-zA-Z]*_.. a string that begins withaand has an underscore somewhere in it, but arbitrary alphabets in between.
– muru
Nov 20 at 5:54
1
@mandrake00 do read Stéphane Chazelas's edit on the answer as well.
– muru
Nov 20 at 6:14
add a comment |
up vote
5
down vote
[A-Z]* is zero or more occurrences of [A-Z]. There are zero occurrences of [A-Z] in ##2, so the line matches. You probably want one or more (1, (or + with GNU grep or compatible), or + with the -E option enabling EREs), or simply ##[A-Z] as if it matches ##[A-Z], it also matches ##[A-Z]+ and vice-versa.
Also note that except in the C/POSIX locale, what is matched by [A-Z] is unspecified and the list of characters (or even possibly collation elements made of several characters) it matches varies with the locale and operating system. On GNU systems, it's generally only characters of the Latin script (including things like Dž or É) often only uppercase ones, but sometimes also lowercase ones including the English a-z letters (like in the Thai locale for Thailand on Ubuntu 18.04 at least). You get much more exotic lists in some non-GNU systems like Solaris. To match on ABCDEFGHIJKLMNOPQRSTUVWXYZ only, use [ABCDEFGHIJKLMNOPQRSTUVWXYZ].
edited Nov 20 at 6:14
Stéphane Chazelas
294k54555898
answered Nov 20 at 5:43
muru
35.1k581154
Thank you. ...grep '#[A-Z]+' works. But still amused by "Zero or more matches"... Is it helpful anywhere(any example)? searching for "zero matches" is same as not searching for it at all, isn't it?
– mandrake00
Nov 20 at 5:49
1
At the start or end of a regex, it isn't that useful, but in between, sure. Saya[a-zA-Z]*_.. a string that begins withaand has an underscore somewhere in it, but arbitrary alphabets in between.
– muru
Nov 20 at 5:54
1
@mandrake00 do read Stéphane Chazelas's edit on the answer as well.
– muru
Nov 20 at 6:14
add a comment |
up vote
5
down vote
up vote
5
down vote
[A-Z]* is zero or more occurrences of [A-Z]. There are zero occurrences of [A-Z] in ##2, so the line matches. You probably want one or more (1, (or + with GNU grep or compatible), or + with the -E option enabling EREs), or simply ##[A-Z] as if it matches ##[A-Z], it also matches ##[A-Z]+ and vice-versa.
Also note that except in the C/POSIX locale, what is matched by [A-Z] is unspecified and the list of characters (or even possibly collation elements made of several characters) it matches varies with the locale and operating system. On GNU systems, it's generally only characters of the Latin script (including things like Dž or É) often only uppercase ones, but sometimes also lowercase ones including the English a-z letters (like in the Thai locale for Thailand on Ubuntu 18.04 at least). You get much more exotic lists in some non-GNU systems like Solaris. To match on ABCDEFGHIJKLMNOPQRSTUVWXYZ only, use [ABCDEFGHIJKLMNOPQRSTUVWXYZ].
edited Nov 20 at 6:14
Stéphane Chazelas
294k54555898
answered Nov 20 at 5:43
muru
35.1k581154
[A-Z]* is zero or more occurrences of [A-Z]. There are zero occurrences of [A-Z] in ##2, so the line matches. You probably want one or more (1, (or + with GNU grep or compatible), or + with the -E option enabling EREs), or simply ##[A-Z] as if it matches ##[A-Z], it also matches ##[A-Z]+ and vice-versa.
Also note that except in the C/POSIX locale, what is matched by [A-Z] is unspecified and the list of characters (or even possibly collation elements made of several characters) it matches varies with the locale and operating system. On GNU systems, it's generally only characters of the Latin script (including things like Dž or É) often only uppercase ones, but sometimes also lowercase ones including the English a-z letters (like in the Thai locale for Thailand on Ubuntu 18.04 at least). You get much more exotic lists in some non-GNU systems like Solaris. To match on ABCDEFGHIJKLMNOPQRSTUVWXYZ only, use [ABCDEFGHIJKLMNOPQRSTUVWXYZ].
edited Nov 20 at 6:14
Stéphane Chazelas
294k54555898
answered Nov 20 at 5:43
muru
35.1k581154
edited Nov 20 at 6:14
Stéphane Chazelas
294k54555898
edited Nov 20 at 6:14
Stéphane Chazelas
294k54555898
edited Nov 20 at 6:14
Stéphane Chazelas
294k54555898
294k54555898
answered Nov 20 at 5:43
muru
35.1k581154
answered Nov 20 at 5:43
muru
35.1k581154
answered Nov 20 at 5:43
muru
35.1k581154
35.1k581154
Thank you. ...grep '#[A-Z]+' works. But still amused by "Zero or more matches"... Is it helpful anywhere(any example)? searching for "zero matches" is same as not searching for it at all, isn't it?
– mandrake00
Nov 20 at 5:49
1
At the start or end of a regex, it isn't that useful, but in between, sure. Saya[a-zA-Z]*_.. a string that begins withaand has an underscore somewhere in it, but arbitrary alphabets in between.
– muru
Nov 20 at 5:54
1
@mandrake00 do read Stéphane Chazelas's edit on the answer as well.
– muru
Nov 20 at 6:14
add a comment |
Thank you. ...grep '#[A-Z]+' works. But still amused by "Zero or more matches"... Is it helpful anywhere(any example)? searching for "zero matches" is same as not searching for it at all, isn't it?
– mandrake00
Nov 20 at 5:49
1
At the start or end of a regex, it isn't that useful, but in between, sure. Saya[a-zA-Z]*_.. a string that begins withaand has an underscore somewhere in it, but arbitrary alphabets in between.
– muru
Nov 20 at 5:54
1
@mandrake00 do read Stéphane Chazelas's edit on the answer as well.
– muru
Nov 20 at 6:14
Thank you. ...grep '#[A-Z]+' works. But still amused by "Zero or more matches"... Is it helpful anywhere(any example)? searching for "zero matches" is same as not searching for it at all, isn't it?
– mandrake00
Nov 20 at 5:49
Thank you. ...grep '#[A-Z]+' works. But still amused by "Zero or more matches"... Is it helpful anywhere(any example)? searching for "zero matches" is same as not searching for it at all, isn't it?
– mandrake00
Nov 20 at 5:49
1
1
At the start or end of a regex, it isn't that useful, but in between, sure. Say
a[a-zA-Z]*_ .. a string that begins with a and has an underscore somewhere in it, but arbitrary alphabets in between.– muru
Nov 20 at 5:54
At the start or end of a regex, it isn't that useful, but in between, sure. Say
a[a-zA-Z]*_ .. a string that begins with a and has an underscore somewhere in it, but arbitrary alphabets in between.– muru
Nov 20 at 5:54
1
1
@mandrake00 do read Stéphane Chazelas's edit on the answer as well.
– muru
Nov 20 at 6:14
@mandrake00 do read Stéphane Chazelas's edit on the answer as well.
– muru
Nov 20 at 6:14
add a comment |
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