Hi
I have a file with data arranged into columns. The first column is the chromosome name.
When I use grep to subset only rows with chr1, I get chr1 but also chr10, chr11,..
How do I get only rows with chr1?
grep chr1 filein > fileout
head fileout
chr1 59757841
chr11 108258691 ... (2 Replies)
Hi,
I'm struggling with a regex that would match a 'b' that follows an 'a' and is at the end of a string of non-white characters. For example:
Line 1: aba abab b abb aab bab baa
I can find the right strings but I'm lacking knowledge of how to "discard" the bits that precede bs.... (2 Replies)
Hi all,
any idea how to match the following:
char*<no or any string or space> buf and
char *<no or any string or space> buf
i need to capture the buf characters too.
currently i need two checks to cover this:
#search char* <any string> buf or char *<any string> buf
@noarray =... (2 Replies)
Hello All
I have file which contain sample data like below -
test.txt
----------------------------------------------
jambesh aaa india
trxxx
sdasd
mentor
asss
light
train
bbblah
---------------------------------------------
I want to write a regX which would print only those... (4 Replies)
Hi all,
I am looking for a regex syntax to match repeated appearance. Likes,
']+]+' matches for string '65A SOME MORE AND 78B'
Now, this gets messy if I need to extract all such repeated appearance. I don't want to write ] four or five times for matching repeated appearance.
Thanks in... (2 Replies)
hi everyone
suppose we have two scenario
echo ABCD | grep \{4\}
DATE
echo SYSDATE | grep \{4\}
SYSDATE
i want to match the string of four length only please help (5 Replies)
Hi Everybody!
I need some help with a regular expression in Perl that will match files named messages, but also files named message.1, message.2 and so on. So really I need one that will find messages and messages that might be followed by a period and a digit without matching other files like... (2 Replies)
I cannot seem to get this to work correct:
my ($k, $v) = split(/F/, $fc{$DIR}{symbolic}, 2);
Below is the input (the $fc{$DIR}{symbolic} variable):
QMH2562 FW:v5.06.03 DVR:v8.03.07.15.05.09-kbut i also need it to break on FV:
Emulex NC553i FV4.2.401.6 DV8.3.5.86.2pthe code above... (2 Replies)
Using a regular expression, I would like multiple lines to be matched.
By default, a period (.) matches any character except newline. However, (?s) and /s modifiers are supposed to force . to accept a newline and to match any character including a newline.
However, the following two perl... (4 Replies)
echo 20110101 | awk '{ print match($0,/^((17||18||19||20)|)-*(|0|1)-*(|0||3)$/))
I am getting a match for the above, where as it shouldn't, as there is no hyphen in the echoed date.
Another question is what is the difference between || and | in the above statement (4 Replies)
Discussion started by: tostay2003
4 Replies
LEARN ABOUT PLAN9
regexp
REGEXP(6) Games Manual REGEXP(6)NAME
regexp - regular expression notation
DESCRIPTION
A regular expression specifies a set of strings of characters. A member of this set of strings is said to be matched by the regular
expression. In many applications a delimiter character, commonly bounds a regular expression. In the following specification for regular
expressions the word `character' means any character (rune) but newline.
The syntax for a regular expression e0 is
e3: literal | charclass | '.' | '^' | '$' | '(' e0 ')'
e2: e3
| e2 REP
REP: '*' | '+' | '?'
e1: e2
| e1 e2
e0: e1
| e0 '|' e1
A literal is any non-metacharacter, or a metacharacter (one of .*+?[]()|^$), or the delimiter preceded by
A charclass is a nonempty string s bracketed [s] (or [^s]); it matches any character in (or not in) s. A negated character class never
matches newline. A substring a-b, with a and b in ascending order, stands for the inclusive range of characters between a and b. In s,
the metacharacters an initial and the regular expression delimiter must be preceded by a other metacharacters have no special meaning and
may appear unescaped.
A matches any character.
A matches the beginning of a line; matches the end of the line.
The REP operators match zero or more (*), one or more (+), zero or one (?), instances respectively of the preceding regular expression e2.
A concatenated regular expression, e1e2, matches a match to e1 followed by a match to e2.
An alternative regular expression, e0|e1, matches either a match to e0 or a match to e1.
A match to any part of a regular expression extends as far as possible without preventing a match to the remainder of the regular expres-
sion.
SEE ALSO awk(1), ed(1), sam(1), sed(1), regexp(2)REGEXP(6)