Sponsored Content
Top Forums Shell Programming and Scripting How to store regular expression in a variable? Post 302952201 by Don Cragun on Friday 14th of August 2015 05:04:49 PM
Old 08-14-2015
Note that you don't grep a folder (usually called a directory in UNIX and Linux environments). The grep utility searches for text in the contents of text files (not directories on most systems).

If you're trying to count the number of files in a directory that have names matching the globbing pattern stored in your shell variable named (confusingly) file_name, you could try something like:
Code:
ls $file_name | wc -l

which should work as long as there aren't any newline characters in your file names. If you have users who create filenames containing newline characters, or if you just want to use shell built-ins, a fast way to get what you want is:
Code:
set -- $file_name
echo $#

(assuming that you aren't using command line arguments or have already gathered what you need from them, and assuming that at least one file matching your pattern exists) or, if there might not be any matching files (but there also might be a file with a name that is your pattern):
Code:
set -- $file_name
if [ "$file_name" = "$1" ] && [ ! -e "$1" ]
then	echo 0
else	echo $#
fi

 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

regular expression using a variable

hello, I use AIX with ISM PILOT, I want to match something with a varible like this : $variable = 10 #this variable is the number of the job "$variable STARTED" # the pattern how can use this variable to match it with the word STARTED Tanks (0 Replies)
Discussion started by: barribar
0 Replies

2. Shell Programming and Scripting

compare variable against regular expression?

is it possible? if so, how? i want to check a variable whether is it a number or letter in an if-else statement (6 Replies)
Discussion started by: finalight
6 Replies

3. Shell Programming and Scripting

Awk's variable in regular expression

Anyone know how I will use awk's variable in a regular expression? This line of code of mine is working, the value PREMS should be a variable: awk '$1 ~ /PREMS/ { if(length(appldata)+2 >= length($1)) print $0; }' appldata=$APPLDATA /tmp/file.tmp The value of APPLDATA variable is PREMS. ... (2 Replies)
Discussion started by: Orbix
2 Replies

4. Shell Programming and Scripting

AWK - compare $0 to regular expression + variable

Hi, I have this script: awk -v va=45 '$0~va{print}' flo2 That returns: "4526745 1234 " (this is the only line of the file "flo2". However, I would like to get "va" to match the begining of the line, so that is "va" is different than 45 (eg. 67, 12 ...) I would not have any output. That... (3 Replies)
Discussion started by: jolecanard
3 Replies

5. Shell Programming and Scripting

Passing Variable to Regular Expression

Hi All, Below is a sample code: print "Enter the Name: "; my $Name = <>; print "Word is $Name"; open (FH,"AIDNameList.txt"); while (<FH>) { my $line; print "Word is $Name"; for $line(<FH>)... (12 Replies)
Discussion started by: jisha
12 Replies

6. 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

7. Shell Programming and Scripting

passing a regex as variable to awk and using that as regular expression for search

Hi All, I have a sftp session log where I am transferring multi files by issuing "mput abc*.dat". The contents of the logfile is below - ################################################# Connecting to 10.75.112.194... Changing to: /home/dasd9x/testing1 sftp> mput abc*.dat Uploading... (7 Replies)
Discussion started by: k_bijitesh
7 Replies

8. UNIX for Dummies Questions & Answers

grep with variable and regular expression

i have a command line like this in csh script grep -i "$argv$" which i wanted to select the line ending with string provided as argument but it couldn't interpret the '$' (ending with).. any help? (3 Replies)
Discussion started by: ymc1g11
3 Replies

9. 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

10. Shell Programming and Scripting

Regular expression as a variable

I'm trying to use a series of regular expressions as variables but can't get it to behave properly. You can see below what I'm trying to do. Here with lowercase a-z and the same with uppercase, numbers 0-9 and again with a set of special characters, without having to type out every single... (3 Replies)
Discussion started by: 3therk1ll
3 Replies
regex(3)						     Library Functions Manual							  regex(3)

Name
       re_comp, re_exec - regular expression handler

Syntax
       char *re_comp(s)
       char *s;

       re_exec(s)
       char *s;

Description
       The  subroutine	compiles  a string into an internal form suitable for pattern matching.  The subroutine checks the argument string against
       the last string passed to

       The subroutine returns 0 if the string s was compiled successfully; otherwise a string containing an  error  message  is  returned.  If	is
       passed 0 or a null string, it returns without changing the currently compiled regular expression.

       The  subroutine returns 1 if the string s matches the last compiled regular expression, 0 if the string s failed to match the last compiled
       regular expression, and -1 if the compiled regular expression was invalid (indicating an internal error).

       The strings passed to both and may have trailing or embedded newline characters; they are terminated by	nulls.	 The  regular  expressions
       recognized are described in the manual entry for given the above difference.

Diagnostics
       The subroutine returns -1 for an internal error.

       The subroutine returns one of the following strings if an error occurs:

       No previous regular expression
       Regular expression too long
       unmatched (
       missing ]
       too many () pairs
       unmatched )

See Also
       ed(1), ex(1), egrep(1), fgrep(1), grep(1)

																	  regex(3)
All times are GMT -4. The time now is 04:51 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy