When asking regex questions, always add the tag for the specific programming language or tool (e.g., Perl, Python, or Java; vi, emacs, or ɢɴᴜ grep; etc.) you are using.

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18
votes
1answer
469 views

Why bracket a single letter in a grep regex?

I've seen several instances where people are doing this: grep [f]oobar But I don't understand why that is preferable to grep foobar
13
votes
1answer
207 views

How do I make sec ignore a timestamp properly

I have a rule that is set up like so; In /etc/sec/rules.d I have; type=SingleWithSuppress ptype=regexp pattern=(\S+) sshd\[\d+\]: PAM \d+ more authentication failures\; logname=.* uid=.* euid=.* tty=...
10
votes
2answers
38k views

Nginx: location regex for multiple paths with backend

I have two locations in nginx config that work: location ^~ /media/ { proxy_pass http://backend.example.com; } location ^~ /static/ { proxy_pass http://backend.example.com; } How can I combine ...
10
votes
1answer
1k views

nginx pcre_compile error when using quantifiers

I'm having an issue with aliasing. I want to append up to the first 4 digits of the file as part of the directory. (like '../123456.jpg'=>'../123/123456.jpg' and '../12.png'=>'../12/12.png') Here is ...
10
votes
3answers
12k views

Nginx location regex doesn't work with proxy pass

I'm trying to get these 2 location directives working in Nginx but I'm getting some errors back when booting Nginx. location ~ ^/smx/(test|production) { proxy_pass http://localhost:8181/...
9
votes
3answers
13k views

nginx rewrite append a parameter at the end of an url

I need to configure my reverse proxy so that the following parameter will be added at the end of the url: &locale=de-de This almost works: rewrite ^(.*)$ $1&locale=de-de break; However, the ...
8
votes
2answers
4k views

Grepping for CIDR ranges

From time to time I want to grep CIDR ranges out of my Apache log files. This is easy for ranges that fall on the natural boundaries (/8, /16 and /24) but not so easy for other ranges such as /17 and ...
8
votes
4answers
3k views

Searching for literal “> \” using ack-grep

I am looking for lines that literally have a greater than character (a ">") followed by a space followed by a backslash character (a "\") i.e., a line with this: > \ I thought escaping would allow ...
8
votes
4answers
13k views

Using sed to remove both an opening and closing square bracket around a string

I'm running this command in a bash shell on Ubuntu 12.04.1 LTS. I'm attempting to remove both the [ and ] characters in one fell swoop, i.e. without having to pipe to sed a second time. I know square ...
8
votes
1answer
5k views

What are PCRE limits?

In ModSecurity there are PCRE limits exceeded errors. I know I can fix this by setting rules such as: SecPcreMatchLimit 150000 SecPcreMatchLimitRecursion 150000 But, what are these rules actually ...
8
votes
1answer
2k views

Ack search for literal strings [closed]

I am sick of having to escape things when I want to search for part of an html tag. How can I ack search for exactly what I type without having to escape stuff? e.g. ack-grep 'console.log(foo' I ...
8
votes
1answer
174 views

Is there a tool that can top-ify an input stream?

I come across quite a few use cases where it would be very useful to take input from a (usually newline-delimited) stream and summarise it in a top-like fashion (see top, iotop, etc). A kind of on-...
7
votes
2answers
15k views

nginx url rewriting. i just don't get it

Ok, an example url is http://www.mysite.com/?p=account&view=settings the p uri is a constant. all urls have it. the view is one of many optional uri. i've tried to understand url rewriting ...
6
votes
2answers
5k views

rsync: How to exclude Dotfiles only in topmost directory?

When performing backups under Bash with rsync, I'm trying to exclude all dotfiles and hidden directories in the top directory, but not those in otherwise targeted directories. For example: /copyme.c ...
6
votes
4answers
6k views

nginx rewrite base url

I would like the root url http://www.example.com to redirect to http://www.example.com/something/else This is because some weird WP plugin always sets a cookie on the base url, which doesn't let ...
5
votes
6answers
11k views

Renaming files in linux with a regex

I had a group of files that I'd like to consistently rename, the files are named things like "System-Log-01-01-2009-NODATA.txt" "Something-Log-01-01-2009-NODATA.txt" And I wanted them as lowercase, ...
5
votes
3answers
2k views

Bash command for regular expression substitution

What bash command can be used for regex substitution on a pipe? cat foo.txt | someprogram
5
votes
2answers
1k views

Is it possible to get the matched regex from within the apache LocationMatch directive?

I'm wondering if the following code should be working: <LocationMatch "/(.*)([/])?(.*)"> Order allow,deny Allow from all AuthType Basic AuthName "Git" AuthUserFile /git/....
5
votes
5answers
913 views

Globally Coloring the Terminal by Regex

I know many programs use color - (vim, ack, color-ls to name a few) but there are still many cases where you're stuck with black and white. There are scripts that will color output based on regular ...
5
votes
1answer
5k views

How do I format this regex so it will work in fail2ban?

I've just installed fail2ban on my CentOS server in response to an SSH brute force attempt. The default regular expressions in fail2ban's sshd.conf file do not match any entries in audit.log, which ...
5
votes
1answer
9k views

Nginx location regex is not matching

The following has been working to cache css and js for me: location ~ "^(.*)\.(min.)?(css|js)$" { expires max; } results: $ curl -I http://mysite.com/test.css HTTP/1.1 200 OK Server: nginx ...
4
votes
2answers
3k views

Why does this regex not work on linux?

prescript: I am not sure where this question belongs i cant say it works on windows but from my understanding this regex is correct and how i would write it (except maybe the ^ at the beginning) ...
4
votes
2answers
5k views

How can I route some emails to a script in Postfix?

How do I route all emails directed to user-*@example.com (i.e. user-1234@example.com) to a pipe command in Postfix? The idea is to create craigslist-style anonymization by assigning dynamic email ...
4
votes
3answers
8k views

Regex for sed to grab multiple lines or a better way?

I'm creating a script that connects to a server and dumps the output to a tempfile. I want to use sed in the script to grab specific information from the temp file. The output would always have the 80 ...
4
votes
5answers
13k views

Copy multiple folders to a single destination with robocopy

I'm looking for a solution to use robocopy to copy several folders from a directory onto a distant network share. I want to choose several folders out of a directory that contains hundreds of folders ...
4
votes
2answers
7k views

How to exclude files from TAR archive using regular expressions?

I have a simple question, yet I can't find or solve the answer. I want to make a tar archive, but I want to exclude some files from it using regular expression. Example of the file to exclude is this:...
4
votes
1answer
6k views

Apache LocationMatch regex behaviour does not seem correct

I am using the LocationMatch directive to set headers upon matching of certain URL patterns: # 1 # Expected matches: //mysite.com/any-page-with-at-least-a-character-and-no-dot <LocationMatch "^/[^\...
4
votes
1answer
185 views

Apache MatchRedirect exception regex

I want to redirect any URL that is Https and hasn't start with "system_" to the same URL with http. for exapmle for this url : https://exsite.tld/some/thing/that/not/start/with/pattern to : http:/...
4
votes
2answers
365 views

Why does a $1 backreference work in a rewrite with no subgroups?

Someone I'm working with committed a RewriteRule such as the following to SVN: RewriteRule ^admin/ebay.*$ /yii.php/$1 [L] I warned him that it may not work because there is no subgroup in the match ...
4
votes
1answer
3k views

nginx error log Grok pattern

I am having trouble getting the following nginx error log message to parse in the grok debugger. I have a feeling there is a stupid trick that I should use but can't figure out what it may be. ...
3
votes
6answers
9k views

Don't need the whole line, just the match from regular expression

I simply need to get the match from a regular expression: $ cat myfile.txt | SOMETHING_HERE "/(\w).+/" The output has to be only what was matched, inside the parenthesis. Don't think I can use ...
3
votes
2answers
9k views

How do I match a wildcard host in ACL lists in HAproxy?

I have the following lines in my haproxy.conf: acl valid_domains hdr(Host) -i mysite.com images.mysite.com docs.mysite.com admin.mysite.com redirect location http://mysite.com/invalid_domain if !...
3
votes
4answers
1k views

Extract repository name from GitHub url in bash

Given ANY GitHub repository url string like: git://github.com/some-user/my-repo.git or git@github.com:some-user/my-repo.git or https://github.com/some-user/my-repo.git What is the best way in ...
3
votes
2answers
677 views

egrep matching group not printing?

I'm trying to create a bash script that will grep lines from a file using egrep. I've created the regex that should group the information I want, the issue is trying to get the output. I've been ...
3
votes
4answers
805 views

Searching for a tail tool for Linux to colorize and suppress lines by regx?

Is there any tool that does both, colorize and filtering lines to suppress form output by regex?
3
votes
1answer
4k views

Fail2Ban SASL Filter Misses Failed Logins

I am using fail2ban on my mail server. I discovered this morning that there were some 5000 failed login attempts (in the course of 1 hour) via SMTP that didn't get picked up by my sasl filter. Here ...
3
votes
1answer
1k views

Bash: How do I copy timestamps using touch and regex?

Since this is more of a Bash question I think this is better suited for serverfault than superuser, even though I'm talking about media files. I had to make a batch conversion of several media files, ...
3
votes
1answer
920 views

Modify fail2ban failregex to match failed public key authentications via ssh

fail2ban doesn't recognize failed public key ssh logins and I assume that this can be solved by modifying the failregex of /etc/fail2ban/filter.d/sshd.config to match the following line: <date> ...
3
votes
2answers
4k views

Regex negative look-ahead is not working for mod_rewrite between different Apache versions

I have a mod_rewrite line that works under Apache 2.2, but not under Apache 1.3: RewriteRule ^(?!index.php)(?!skin/)(?!js/)(.+) /index.php?file=$1 [NC,L] If I lose the ...
3
votes
2answers
1k views

Replace Wildcard Character in Filenames

I can't get this to work: I have hundreds of files that our database developer has foolishly put asterisks in, so that we have files named like this: *1*_Floorplan.jpg I need to recursively (two ...
3
votes
3answers
3k views

Nagios not accepting regex in command

I have this command defined: define command{ command_name check_http_sane command_line $USER1$/check_http -H $HOSTNAME$ -r "HTTP/1.1 (200|301|302|303|304|307|401|418|426)" } When I run it manually ...
3
votes
4answers
5k views

apache locationmatch negative regex

I'm trying to expose a location through Apache. Normally, I have this block in my vhost that says <Location /> AuthType Basic AuthUserFile /web/.htpasswd AuthName "Test Site" ...
3
votes
2answers
73 views

ubuntu 14.04 Apache 2.4.7 mpm_event Files and FilesMatch not working

We recently switched our Apache 2.4.7 mode from mpm_pre-fork to mpm_event. Since then we haven't been able to get our Files directive to work. <Files "*.php"> Header set Cache-Control "no-...
3
votes
1answer
1k views

How do I use “catchall” in my postfix alias?

I have this in my main.cnf: alias_maps= regexp:/etc/aliases Inside that file, I have: /^reply*$/: jjj Now, when I send it to reply-124233@mydomain.com, postfix bounces it because Recipient ...
3
votes
1answer
63 views

Regex location block not working in NGINX

I have a pretty simple location block in my nginx conf that looks like this: location ~* ^\/[a-z0-9]{24}$ { // do some things } I'm attempting to catch urls that end in a Mongo ObjectId. eg: ...
3
votes
1answer
2k views

nginx regex characters that require quoting?

So I was configuring nginx today and I hit a weird problem. I was trying to match a location like this: location ~ ^/([0-9]+)/(.*) { # do proxy redirects } ...for URLs like "http://my.domain....
3
votes
1answer
2k views

SetEnvIf regex for setting Content-Disposition HTTP header

I am attempting to use the IHS 7.0/apache 2.2 SetEnvIf directive to set the filename of a downloaded file based on a url parameter. I think I am pretty close, however if there is a space (encoded or ...
2
votes
1answer
7k views

Nginx redirect all old domain subdomains to new one

I had a very long domain, so I decided to change it to a shorter and more friendly one. But since I have a lot of subdomains (in fact, I have a subdomain wildcard), I wanted to keep the subdomain ...
2
votes
3answers
51k views

Most simple way of extracting substring in Unix shell?

What's the most simple way to extract substring on Unix shell (with regex)? Simple means: less feature less options less study Update I realized regex itself is conflicting with simplicity, and ...
2
votes
5answers
5k views

What is a good bulk find / replace tool for windows? [closed]

I'm looking to find / replace in alot of files and was wondering if anybody could recommend some good tools for Windows. I'd prefer them to be free. Thanks