08-26-2017
Quote:
Originally Posted by
John K
...
Where can I read more about "\s" ? What is this operator called ? (So that I can google about it )
It's a "metacharacter" or a "shorthand character class" in a regular expression.
Any book, blog or webpage on regular expressions should mention it.
Here's the Wikipedia page on regular expressions; search for "\s" on that page:
Regular expression - Wikipedia
Here's Jan Goyvaert's website on regular expressions in general. Pretty decent stuff.
Regexp Tutorial - Shorthand Character Classes
In particular, if you are looking for using regular expressions in the Vim editor, then this page looks pretty good:
Vim Regular Expressions 101
The books mentioned at the bottom of the above page are good too.
Jeffrey Friedl's book on regular expressions is the most advanced and a gold mine of information.
These 2 Users Gave Thanks to durden_tyler For This Post:
10 More Discussions You Might Find Interesting
1. Shell Programming and Scripting
Hi There!
My final task for today is to delete lines starting with certain numbers
for e.g., my text block is
and i want to delete all lines starting with 11 or 17 or 21
I know i can use multiple sed commands like
sed '/^11,/d' <filename>
sed '/^17,/d' <filename>
sed '/^21,/d'... (2 Replies)
Discussion started by: orno
2 Replies
2. Shell Programming and Scripting
Hi All,
Was wondering how I can do the following....
I have a String as follows
"ACCTRL000005022RRWDKKEEDKDD...."
This string can be in a file called tail.out or in a Variable called $VAR2
Now I have another variable called $VAR1="000004785" (9 bytes long), I need the content of... (5 Replies)
Discussion started by: mohullah
5 Replies
3. Shell Programming and Scripting
Hi,
I have to search a word in a text file and then I have to delete lines above from the word searched . For eg suppose the file is like this:
Records
P1
10,23423432
,77:1
,234:2
P2
10,9089004
,77:1
,234:2
,87:123
,9898:2
P3
456456
P1
:123,456456546
P2
abc:324234 (2 Replies)
Discussion started by: vsachan
2 Replies
4. Shell Programming and Scripting
i have a file sample.txt containing
i want to delete lines starting with 123 neglecting spaces and tabs.
but not lines containing 123. i.e.
i want files sample.txt as
help me
thanxx (4 Replies)
Discussion started by: yashwantkumar
4 Replies
5. Shell Programming and Scripting
Hi, just tried some script, awk, sed for the last 2 hours and now need help.
Let's say I have a huge file of 800,000 lines like this :
It's a tedious job to look through it, I'd like to remove those useless lines in it as there's a few thousands :
Or to be even more precise :
if line1 =... (6 Replies)
Discussion started by: Zurd
6 Replies
6. Shell Programming and Scripting
Sample file:
This is line one,
this is another line,
this is the PRIMARY INDEX line
l ;
This is another line
The command should find the line with “PRIMARY INDEX” and remove the last character from the line preceding it (in this case , comma) and remove the first character from the line... (5 Replies)
Discussion started by: KC_Rules
5 Replies
7. Shell Programming and Scripting
Platform : RHEL 5.8
I have text file called myapplication.log . In this file, I have around 800 lines which start with the followng three strings
PWRBRKER-3493
PWRBRKER-7834
SCHEDULER-ERROR
How can I delete these lines in one go ? (13 Replies)
Discussion started by: omega3
13 Replies
8. Shell Programming and Scripting
Dear all,
I would like to delete even lines starting with "N" together with their respective titles which are actually odd lines.
Below is the example of input file. I would like to remove line 8 and 12 together with its title line, i.e., line 7 and 11, respectively.... (2 Replies)
Discussion started by: huiyee1
2 Replies
9. UNIX for Dummies Questions & Answers
e.g.
File name: File.txt
cat File.txt
Result:
#INBOUND_QUEUE=FAQ1
INBOUND_QUEUE=FAQ2
I want to get the value for one which is not commented out.
Thanks, (3 Replies)
Discussion started by: Tanu
3 Replies
10. Shell Programming and Scripting
Shell : bash
OS : RHEL 6.8
I have a file like below.
$ cat pattern.txt
hello
txt1
txt2
txt3
some other text
txt4
I want to remove all lines in this file except the ones starting with txt . How can I do this ? (4 Replies)
Discussion started by: omega3
4 Replies
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)