Hi all, i have read in one site (i can put link, but is in Czech language ) that regular expressions have some kind of memory. If i understood it propertly when i want to remebmer some part of regexp i just put it between \( and ) and then call it by \1 \2 \3 etc. where \$number is number of memored expression. So i tried some examples bud didnt work for me :
lets say i want to know only UID and HOME from /etc/passwd so i tried followings:
The more formal term is backreference. A backreference stores the part of the string matched by the part of the regular expression inside the parentheses.
I need to pick a part of string lets stay started with specific character and end with specific character to replace using sed command
the line is like this:my audio book 71-skhdfon1dufgjhgf8.wav'
I want to move the characters beginning with - end before.
I have different files with random... (2 Replies)
I have a file that I'm trying to find all the cases of phone number extensions and deleting them. So input file looks like:
abc
x93825
def
13234
x52673
hello
output looks like:
abc
def
13234
hello
Basically delete lines that have 5 numbers following "x". I tried: x\(4) but it... (7 Replies)
what elements does " /^/ " match?
I did the test which indicates that it matches single lowercase character like 'a','b' etc. and '1','2' etc.
But I really confused with that. Because, "/^abc/" matches strings like "abcedf" or "abcddddee".
So, what does caret ^ really mean?
Any response... (2 Replies)
#!/usr/bin/perl
$word = "one last challenge";
if ( $word =~ /^(\w+).*\s(\w+)$/ )
{
print "$1";
print "\n";
print "$2";
}
The output shows that "$1" is with result one and "$2" is with result challenge. I am confused about how this pattern match expression works step by step. I... (8 Replies)
In regular expressions with grep(or egrep), ^ works if we want something in starting of line..but what if we write ^^^ or ^ for pattern matching??..Hope u all r familiar with regular expressions for pattern matching.. (1 Reply)
I have a flat file with the following drug names
Nutropin AQ 20mg PEN Cart 2ml
Norditropin Cart 15mg/1.5ml
I have to extract digits that are before mg i.e 20 and 15 ; how to do this using regular expressions
Thanks
ram (1 Reply)
how to find for a file whose name has all characters in uppercase after 'project'?
I tried this:
find . -name 'project**.pdf'
./projectABC.pdf
./projectABC123.pdf
I want only ./projectABC.pdf
What is the regular expression that correponds to "all characters are capital"?
thanks (8 Replies)
How can i create a regular expression which can detect a new line charcter followed by a special character say * and replace these both by a string of zero length?
Eg:
Input File san.txt
hello
hi ... (6 Replies)