Login or Register to Ask a Question and Join Our Community


Shell Programming and Scripting

Grep using wild card issue

Login to Discuss or Reply to this Discussion in Our Community

 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting Grep using wild card issue
# 1  
Old 05-20-2010
Error Grep using wild card issue
Hi,

I am having a file (file1) having following contents

" xet B - All Divers/All Rivers - - ns - "

Now when i use

Code:
 cat file1 | grep 'RF'

it doesn't returns anything.
But on using
Code:
 cat file1 | grep 'RF*'

shows me this complete line

But in this file there is no word RF, then why grep is showing me this complete line on using RF*.

Thanks
Sarbjit
# 2  
Old 05-20-2010
From the man page of grep:
Quote:
Repetition
A regular expression may be followed by one of several repetition operators:
? The preceding item is optional and matched at most once.
* The preceding item will be matched zero or more times.
+ The preceding item will be matched one or more times.
{n} The preceding item is matched exactly n times.
{n,} The preceding item is matched n or more times.
{,m} The preceding item is matched at most m times.
{n,m} The preceding item is matched at least n times, but not more than m times.
So
Code:
grep 'RF*'

means "search for an uppercase R, followed by 0 or more uppercase F", which matches the 'R' in 'Rivers'.
# 3  
Old 05-20-2010
Because a * stands for "none or any number of the previous character". So a simple "R" in your input is a match.

When using grep, you don't need to pipe input via cut. Just do
Code:
grep RF* file1

# 4  
Old 05-20-2010
Also in this case "*" is not a wildcard, it's a modifier.
# 5  
Old 05-20-2010
Also, In regular expression terms, it is called as quantifiers.
"?" and "+" are the other two.
# 6  
Old 05-20-2010
Quote:
Originally Posted by anchal_khare
"?" and "+" are the other two.
Yes, but as far as I know "?" and "+" are not supported in BRE (grep's default).
# 7  
Old 05-20-2010
Quote:
Originally Posted by verdepollo
Yes, but as far as I know "?" and "+" are not supported in BRE (grep's default).
True for grep.
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Wild card for dir path

I have dir structure like this : /opt/oracle/product/abc/sqlplus/admin/ /opt/oracle/product/def/sqlplus/admin /opt/oracle/product/ghi/sqlplus/admin I am trying to use wildcard ( for dirs abc,def,ghi) ..something like this : cp xyz.txt ... (1 Reply)
Discussion started by: talashil
1 Replies

2. Shell Programming and Scripting

find with wild card [solved]

Can somebody help me with the following syntax? I want to find all files that end with *.arc SUFFIX=".arc" find /tmp -name "\*$SUFFIX" -print 2>/dev/null ---------- Post updated at 03:45 PM ---------- Previous update was at 03:41 PM ---------- got it thanks -name... (0 Replies)
Discussion started by: BeefStu
0 Replies

3. Shell Programming and Scripting

Passing variable and wild card character to grep in Perl

HI All, I have a script that needs to find out a list of files in a directory, i pass the search parameter as an argument. opendir ( DIR, $dir ) || die "Error in opening dir $dirname\n"; @filename1 = (grep {/$File_pattern/ } readdir(DIR)); The problem is my file patterns are like... (1 Reply)
Discussion started by: amit1_x
1 Replies

4. Shell Programming and Scripting

How to send a string to function containing wild card?

Hey All, I am trying to send a string as an input parameter to a function which contains a wild card character - * However the function is taking it as: PS: The directory - '/path/to/my/dir/' has 3 files: file1.out, file2.out, file3.out However I want to disable this wild... (2 Replies)
Discussion started by: paragkalra
2 Replies

5. Shell Programming and Scripting

wild card in if condition not working

Hi, I am using RHEL5. I have following if condition. if In the above condition, if the value of a contains word WARNING, it should match. i.e., WARNING_MESSAGE, CRITICAL WARNING, WARNING ALERT etc. it should match. For b, alert error, ALERT ERROR, ERROR IMMEDIATE ACTION REQUIRED, etc... (2 Replies)
Discussion started by: user7509
2 Replies

6. AIX

df, grep, wild card

Hi, I want to monitor my filesystem capacity and I want to df with grep wildcard for all 9*%. Is this possible? I want to replaced all the existing complicated scripts I have in the system. Thanks, Itik (2 Replies)
Discussion started by: itik
2 Replies

7. Shell Programming and Scripting

Wild card in find perm

Hi, Is there a way to use find command to list the directories for certain permissions. I know we can use find . -type d -perm nnn, where nnn is the permission number . However I wold like to know if I wanna search for wild card permissions i.e 75* / 7* / 55* , as i do not know the actual... (1 Reply)
Discussion started by: braindrain
1 Replies

8. UNIX for Dummies Questions & Answers

How do I pass a wild card as an argument

Hi, I would like to pass a wild card as part of an argument. But when I do it the script views the wild card as text. Example: sFile=MG1A* sort $sFile > $sFile.sorted What I get is MG1A*.sorted The problem is I am passed a series of files where the first few characters like "MG1A"... (2 Replies)
Discussion started by: eja
2 Replies

9. UNIX for Dummies Questions & Answers

ls and wild card - Should be simple!

I am trying to cp files that have F0 as prefix in their name in path p1/p2 to path p3/p4 this command does not work - Why? (I am using HP/UX) cp p1/p2/F0* p3/p4 thanks. (2 Replies)
Discussion started by: GNMIKE
2 Replies

10. UNIX for Dummies Questions & Answers

using if with wild card patterns

Hi, Please help me. Suppose I have a file which contains files like: My file :/tmp/rooh_20020518.lst it consists: ASI00320225041925URD01 ASI00320225041925KER02 ASI00390228095244KER08 ... (1 Reply)
Discussion started by: rooh
1 Replies
Login or Register to Ask a Question