sed uses regular expressions only, you can create a regex to look at the first field only with regex constructs; the ^ is already halfway there, as it forces the match to happen at beginning of line. Suppose the field separator is a vertical bar; then you can just add that after the string you want to search for, to anchor it properly.
This finds "AAA" followed by vertical bar, but only if it is at beginning of line (because of the ^) and ditto for "BBB".
The vertical bar has special meaning to some regular expression engines, just like the ^ -- if you get erratic behavior (all lines matching all the time) then you need to backslash-quote it, like \|. It is unfortunate that there are different dialects of sed so that we can't know for sure whether or not this is an issue in your case.
Last edited by era; 05-14-2008 at 05:52 AM..
Reason: Separator is vertical bar, as per above
Hello. I have an RS/6000 running AIX 4 and I need to be able to see if there are any users that are logged on more than once from the same terminal so I can kick them off to make room for other terminals. 64 connections is the limit. Currently I am doing this:
who | more
and then manually... (11 Replies)
Hi,
Let's say I have these 3 columns;
NGC1234 6 9
SL899 4 1
NGC1075 8 3
SL709 5 2
And I want to sort the data according to the first column (from a to z) like having them as:
NGC1075 8 3
NGC1234 6 9
SL709 5 2
SL899 4 1
Can that be done... (2 Replies)
Dear Gurus,
I need you to advice or suggestion about the best solution to copy data around 200-300G from serverA(location A) to serverB(location B). Normally, I will share folder and then copy but it takes too long time(about 2 days).
Do you have any suggestion or which way should be... (9 Replies)
Hello guys. I need help figuring this one out. It's probably really easy. Thanks in advance!
I have a file say for example containing this:
Rice Food
Carrots Food
Beans Food
Plates Kitchen
Fork Kitchen
Knives Kitchen
I need:
Food Rice, Carrots, Beans
Kitchen Plates, Fork,... (7 Replies)
I have the small script to arrange files of a descending way.
ls -l |sort -r -k4
i wanted for example if I place -d one arranges only the folders or -a to arranges only the files.
Cheers (7 Replies)
Hi All,
I have a long list made of 4 columns containing entries such as the following example:
a b c d
0 0 0 0
1 2 1 2
2 5 3 4
3 8 4 6
4 10 9 8
5 15 8 10So the top row is the header and I need to arrange the data in a way as to... (11 Replies)
My actual data looks like below
i have given only format. i can't give exact data format of my requirement due to some reasons. I this set of data lines about 5000
I need to come up with information in below
exact format of my data set :
Line<space>Number1<space>"somedata":... (1 Reply)
I am fairly new to unix scripting, the problem is i can understand the unix script. but i fail to write. I do not know where to start and how to end.
I am sure this forum will help to achive my dream scriptings in unix. Thanks in adv for your help.
Here I need.. I have list of columns in one... (2 Replies)
Hello,
I'm trying to create multiple commands using a variable input from another file but am not getting any successful results.
Basically, file1.txt contains multiple lines with single words:
<file1.txt>
yellow
blue
black
white
I want to create multiple echo commands with these... (8 Replies)
Hello,
I have some text data that is in the form of multi-line records. Each record ends with the string $$$$ and the next record starts on the next line.
RDKit 2D
15 14 0 0 0 0 0 0 0 0999 V2000
5.4596 2.1267 0.0000 C 0 0 0 0 0 0 0 0 0 0 0 ... (5 Replies)
Discussion started by: LMHmedchem
5 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)