Regular expression matching

Login or Register for Dates, Times and to Reply

Thread Tools Search this Thread
# 1  
Regular expression matching

I have a variable in my script that gets its value from a procstack output. It could be a number of any length, or it could just be a '1' with 0 or more white spaces around it. I would like to detect when this variable is just a 1 and not a 1234, for example. This is as far as I got:

if [[ ${var1} = ^1$ ]] then
echo $var1
else echo "Bad"

And the execution goes like this:

How can I get it to check that the value is just 1, with either spaces or not around it, but cernainly not digits?

Thanks in advance. I get the feelign this is quite easy-peasy but I canīt get my head around regular expressions yet.


Last edited by zxmaus; 03-30-2010 at 07:52 AM.. Reason: added code tags
# 2  
Your code only matches a single 1 when it is the first and last character on a line.

You need to add more regex than that!
# 3  
You can use expr:

expr "$var" : '^ *1 *$' >/dev/null && echo OK

# 4  
if x is the desired output, Add some number , say N in the output and try to check id the final output is x+N Smilie

'1' + 1 = '2'
and is also
' 1 ' + 1 = '2'
Login or Register for Dates, Times and to Reply

Previous Thread | Next Thread
Thread Tools Search this Thread
Search this Thread:
Advanced Search

Test Your Knowledge in Computers #720
Difficulty: Medium
Alan Minsky was an adviser on Stanley Kubrick's movie 2001: A Space Odyssey.
True or False?

10 More Discussions You Might Find Interesting

1. UNIX for Advanced & Expert Users

sed: -e expression #1, char 0: no previous regular expression

Hello All, I'm trying to extract the lines between two consecutive elements of an array from a file. My array looks like: problem_arr=(PRS111 PRS213 PRS234) j=0 while } ] do k=`expr $j + 1` sed -n "/${problem_arr}/,/${problem_arr}/p" problemid.txt ---some operation goes... (11 Replies)
Discussion started by: InduInduIndu
11 Replies

2. Shell Programming and Scripting

regular expression matching whole words

Hi Consider the file this is a good line when running grep '\b(good|great|excellent)\b' file5 I expect it to match the line but it doesn't... what am i doing wrong?? (ultimately this regex will be in a awk script- just using grep to test it) Thanks, Storms (5 Replies)
Discussion started by: Storms
5 Replies

3. UNIX for Dummies Questions & Answers

delete lines matching a regular expression

I have a very large file (over 700 million lines) that has some lines that I need to delete. An example of 5 lines of the file: HS4_80:8:2303:19153:193032 153 k80:138891 HS4_80:8:2105:5544:43174 89 k88:81949 165 k88:81949 323 0 * = 323 0 ... (6 Replies)
Discussion started by: pathunkathunk
6 Replies

4. Programming

Perl: How to read from a file, do regular expression and then replace the found regular expression

Hi all, How am I read a file, find the match regular expression and overwrite to the same files. open DESTINATION_FILE, "<tmptravl.dat" or die "tmptravl.dat"; open NEW_DESTINATION_FILE, ">new_tmptravl.dat" or die "new_tmptravl.dat"; while (<DESTINATION_FILE>) { # print... (1 Reply)
Discussion started by: jessy83
1 Replies

5. Shell Programming and Scripting

Hidden Characters in Regular Expression Matching Perl - Perl Newbie

I am completely new to perl programming. My father is helping me learn said programming language. However, I am stuck on one of the assignments he has given me, and I can't find very much help with it via google, either because I have a tiny attention span, or because I can be very very dense. ... (4 Replies)
Discussion started by: kittyluva2
4 Replies

6. Shell Programming and Scripting

Matching single quote in a regular expression

I trying to match the begining of the following line in a perl script with a regular expression. $ENV{'ORACLE_HOME'} I tried this regluar expession: /\$ENV\{\'ORACLE_HOME\'\}/ Instead of match, I got a blank prompt > It seems to be a problem with the single quote. If I take it... (11 Replies)
Discussion started by: JC9672
11 Replies

7. Shell Programming and Scripting

Regular expression matching in BASH (equivalent of =~ in Perl)

In Perl I can write a condition that evaluates a match expression like this: if ($foo =~ /^bar/) { do blah blah blah } How do I write this in shell? What I need to know is what operator do I use? The '=~' doesn't seem to fit. I've tried different operators, I browsed the man page for... (3 Replies)
Discussion started by: indiana_tas
3 Replies

8. Shell Programming and Scripting

Help: Regular Expression for Negate Matching String

Hi guys, as per subject I am having problem with regular expressions. Example, if i got a string "javax.servlet.http.HttpServlet.service" that may occurred anywhere within a text file. How can I used the negate pattern matching of regular expression? I tried the below pattern but it... (4 Replies)
Discussion started by: DrivesMeCrazy
4 Replies

9. Programming

Regular Expression matching in PERL

I am trying to read a file and capture particular lines into different strings: LENGTH: Some Content here TEXT: Some Content Here COMMENT: Some Content Here I want to be able to get (LENGTH: .... ) into one array and so on... I'm trying to use PERL in slurp mode but for some reason... (8 Replies)
Discussion started by: Legend986
8 Replies

10. Shell Programming and Scripting

Regular expression matching a new line

I have written a script to test some isdn links in my network and I am trying to format the output to be more readable. Each line of the output has a different number of digits as follows... Sitename , spid1 12345678901234 1234567890 1234567 , spid2 1234567890 1234567890 1234567 Sitename , ... (1 Reply)
Discussion started by: drheams
1 Replies

Featured Tech Videos