How does this sed expression to remove non-alpha characters work?
Hello!
I know that this expression gets rid of non-alphanumeric characters:
and I understand that it is replacing them with nothing - hence the '//'-, but I don't understand how it's doing it.
It seems it's finding strings that begin with alphanumeric and replacing them with nothing! Obviously that would not give the required output so I'm a little confused and clearly missing something...
Thanks for your help!
Last edited by Don Cragun; 07-24-2013 at 01:48 PM..
Reason: Added CODE tags.
Hi,
Sorry for silly question, but I'm trying to write a perl script to operate a log file that is in following format:
(4)ab=1234/(10)bc=abcdef9876/cd=0....
The number in the brackets is the lenghts of the field, "/" is the field separator. Brackets are not leading every field.
What I'm... (9 Replies)
Hi all,
Suppose I have a file with the contents below, and I only want to print words %S_ then | sort -u.
------------------------------
The %S_MSG that starts with '%.*s' is too long. Maximum length is %d.
The %S_MSG name '%.*s' contains more than the maximum number of prefixes. The... (5 Replies)
Here is my problem.
I have a list of phone numbers that I want to use only the last 4 digits as PINs for something I am working on. I have all the numbers in a file but now I want to be removed all items EXCEPT the last 4 digits.
I have seen sed commands and some grep commands but I am... (10 Replies)
hello, I'm trying to write the fastest sed command possible (large files will be processed) to replace RICH with NICK in a file which looks like this (below) if the occurance of RICH is uppercase, replace with uppercase if it's lowercase, replace with lowercase
SOMTHING_RICH_SOMTHING <- replace... (10 Replies)
I am trying to analyse a large file of sequencing data, example of first 10 lines below,
@HWUSI-EAS656_0044_FC:7:1:2447:1039#GCAATT/1
GNCTATGGCTTGCCGGGCTCAGGGAAGACAATCATAGCCATGAAAATCATGGAAAAGATCAGAAAAACATTTCAA
+HWUSI-EAS656_0044_FC:7:1:2447:1039#GCAATT/1... (1 Reply)
Hi All,
I am new to Unix and trying to run some scripting on a linux box. I am trying to remove the non alphanumeric characters and alpha characters from the following line.
<measResults>883250 869.898 86432.4 809875.22 804609 60023 59715 </measResults>
Desired output is:
883250... (6 Replies)
Hi,
I am new to Sed and would like to know if it is possible to remove the characters .
I have a couple of files with a keyword and would like to remove the substring.
I am Using sed s/// but Its not working
Thanks for your Support
Andrew Borg (2 Replies)
I'm watching a particular expression as it is appended in a line to a file:
tail -f LOG | sed -n /"$@"/p
So whatever value I pass into this script will tail -f the file, but only show me lines that contain the value:
lgwatch expression
However some of the output contains a #20 control... (8 Replies)
I had a string in perl script as below.
Tue Augáá7 03:54:12 2012
Now I need to replace the special character with space.
After removing the special chaacters
Tue Aug 7 03:54:12 2012
Could anyone please help me here for writing the regular expression?
Thanks in advance..
Regards,
GS (1 Reply)
Greetings..
getting the error while execution of the script, correct where i am missing
#!/bin/bash
DATE=`date +%Y-%m-%d:::%H:%M`
HOSTNAME=`hostname`
TXT="/log/temp.txt"
LOGPATH="/log1/commanlogs/"
IP=`/sbin/ifconfig | grep -i inet| head -n1| awk '{print $2}'| awk -F : '{print $2}'`... (7 Replies)
Discussion started by: manju98458
7 Replies
LEARN ABOUT PLAN9
regexp
REGEXP(6) Games Manual REGEXP(6)NAME
regexp - regular expression notation
DESCRIPTION
A regular expression specifies a set of strings of characters. A member of this set of strings is said to be matched by the regular
expression. In many applications a delimiter character, commonly bounds a regular expression. In the following specification for regular
expressions the word `character' means any character (rune) but newline.
The syntax for a regular expression e0 is
e3: literal | charclass | '.' | '^' | '$' | '(' 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)