We all know how annoying those ^M-s can be all over your script or file. ^M is a carriage return, and is commonly seen when files are copied from Windows. All of them can be removed in one step, with vi editor. Open your file in vi and hit escape. Then do like shown below.
%s/{Ctrl+V}{Ctrl+M}//{Enter}
If you want to test if users can ssh to a server with their passwords but your attempt is overridden by your ssh certificate, this is how you can do it.
ssh user@my.hostname.com -o PreferredAuthentications=password
By default, if you try to chown symbolic link, e.g. symlink, it won’t work. User and group of symlink will stay the same after attempt. What you can do is add -h flag in your chown command. This flag stands for –no-dereference and it means »affect symbolic links instead of any referenced file«.
Example:
### symlink is owned by root [root@myserver www]# ls -l lrwxrwxrwx 1 root root 13 May 14 14:51 html -> /var/www/html ### try to chown directory with nginx user and group [root@myserver www]# chown nginx:nginx html ### no changes [root@myserver www]# ls -l lrwxrwxrwx 1 root root 13 May 14 14:52 html -> /var/www/html ### try chown with -h flag [root@myserver www]# chown -h nginx:nginx html ### ownership of symbolic link html is now changed [root@myserver www]# ls -l lrwxrwxrwx 1 nginx nginx 13 May 19 14:52 html -> /var/www/html
By default, WordPress won’t allow you to change username of your administrator account. There are several ways to do this. There are even plugins for this, but I think using plugins for this task is unnecessary and bad idea in general. WordPress is great but consider using as less plugins as you can. Especially bad ones, they are just calling to be hacked by evil guys with too much time. 🙂
Here is how to change administrators username with one simple mysql command.
First, select your wordpress database.
mysql> show tables; +-----------------------+ | Tables_in_sample-blog | +-----------------------+ | wp_commentmeta | | wp_comments | | wp_links | | wp_options | | wp_postmeta | | wp_posts | | wp_snippets | | wp_term_relationships | | wp_term_taxonomy | | wp_termmeta | | wp_terms | | wp_usermeta | | wp_users | +-----------------------+
So in this case I want to change username for my admin user.
mysql> select id, user_login from wp_users; +----+------------+ | id | user_login | +----+------------+ | 1 | admin | | 2 | someuser | +----+------------+
You just have to update user_login field in wp_users table with command below. Of course change id and user_login value to your needs.
mysql> update wp_users set user_login="igor" where id="1"; Query OK, 1 row affected (0.05 sec) Rows matched: 1 Changed: 1 Warnings: 0
Username is now changed. You can login in your wordpress with new username.
mysql> select id, user_login from wp_users; +----+------------+ | id | user_login | +----+------------+ | 1 | igor | | 2 | someuser | +----+------------+
Sometimes your exim mail queue can grow quite large. Especially when some website (WordPress!) is hacked and is sending tons of spam mail. Or when you end up with thousands of frozen mails. You probably don’t want to remove all emails from queue. That would mean legit emails too. You want to specify and delete only specific ones.
For sake of this demonstration we want to delete all emails that contains string domain.com
18h 60K 1b33Uz-000LkN-48 <info@domain.com> (someuser)
info@somedomain.com
Just run command below and all mails with string match doman.com will be deleted from mail queue.
exim -bp | grep "domain.com" | awk {'print $3'} | xargs exim -Mrm
Or for example, in case of frozen mails:
exim -bp | grep froz | awk {'print $3'} | xargs exim -Mrm
CryptoPHP is nasty little shit! A while ago I had a problem with spam on one of our hosting servers. When we ended on several RBL lists, one of them stated that there is a possible way that our machine is infected with CryptoPHP. Hacked files can be very hard to find. PHP code was hidden in false .png files! This pngs were then included in some legit php files, like index.php. So every time index.php was loaded, hacked code inside included png file was loaded too.
Here is how you can find if there are false png files on your system. Just scan your directory with this line:
find -L /path/to/dir/ -type f -name "*.png" -exec file {} + | grep PHP
You could also scan your system for other types of files. Just replace *.png with something elese, for example *.jpg.
Output for legit files will look something like this:
./wp-includes/js/tinymce/skins/wordpress/images/more-2x.png: PNG image data, 3800 x 40, 4-bit colormap, non-interlaced
Output for script that pretends to be regular PNG file – hacks – will look something like this:
./test.png: PHP script, ASCII text
You can simply create backups of specific tables with mysqldump.
mysqldump -u -p databasename table1 table2 table3 ... > mysqldump_file.sql
Sometimes you have a lot of files to transfer and no rsync, only FTP. You don’t want to sit in front of the computer and waiting for files to transfer. If you have access to command line, there is a simple solution on how to transfer all your files through FTP with wget. Once transfer is started you don’t want to close terminal session as you would cancel transfer also. Luckily there is great piece of software named screen. So, you start a new screen session by typing command screen, and run command below. Then you can detach from that screen session with pressing CTRL + A + D. This way file transfer will continue to transfer in background. You can even shut down your computer. When you want to see if all is transfered, you can just attach screen session back with command screen -x.
So in screen, just run this:
wget -m ftp://username:password@ftp.hostname.com
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