I'll begin by saying that I am absolutely no UNIX expert. Having worked with Unix (specifically CentOS) systems for a few years - I've been Googling and learning lots of really essential and overall very useful commands. I've kept a spreadsheet for myself - but figured it may prove to be helpful and time-saving for someone else.
Finding a specific filename on the Unix filesystem in all Sub-Directories
- Let's say you are currently inside /var/www/yoursite directory
- You want to find a file called "barney.jpg" inside "yoursite" directory and all of its sub-directories
- find . -name barney.jpg -type f
Executing a command on several Unix servers at the same time
- In this example, imagine you have a cluster of 7 web-servers named webserver1 through 7
- You want to execute the same command on all 7 machines without having to ssh individually to each machine and executing the same command line.
- The command below will massh into 7 webservers, check the apc.ini file and output a grep search result of "apc.shm_size=256". The commands after -c can be anything, for example "w".
- massh -r webserver[1-7] -c "cat /etc/php.d/apc.ini |grep apc.shm_size=256" -o
- Let's say that your /var/www/yoursite directory is a symbolic link to a release branch
- Example: /var/www/yoursite/ => /var/www/releases/2012_release1/
- To view the physical location inside the symbolic link directory you have to modify the "pwd" command slightly:
- pwd -P
How to grep everything inside a directory including all of its sub-directories?
- In this example you are inside a document root, such as /var/www/yoursite/
- There are hundreds of .php files located in different directories
- You want to find the exact file that references a specific keyword inside it
- For example "whSysopRangeBans"
- grep -r -i 'wgSysopRangeBans' ./
How to remove lines inside a file using VI (VIM Editor) that begin with a specific character
How to Tar Gzip an Entire Directory (create a tarball for entire directory and all sub-dirs)
- In this example you are editing a sample file called example.php
- Imagine that every line in example.php starts with "X" without quotes
- XBuffer do xyz
- XRender zyg
- For some reason you want to find and remove the lines that begin with the X character
- The VIM command for this regular expression delete is:
- :g/^x.*$/d
How to output top 10 requests in your Apache ERROR or ACCESS log
- In this example you are checking your apache request log(s)
- Want to find out what the top 10 requesting IP's are?
- cat /var/log/httpd/yoursite.com-access-20120209.log | awk '{print $1}'| sort -n | uniq -c | sort -rn | head -n10
- Very helpful in quickly identifying malicious scrapers and other issues
How to migrate / move an entire site server to server or sync full sites / directories
- In this example we have two different servers
- You want to sync or move the files from one server to another; from source to destination
- This command will rsync files that are updated or do not exist on the destination directory
- So, if you want to synchronize both directories on two different servers, this command will help.
- Below command assumes you are logged into the source server and you will be connecting/sending files to destination server; you will be syncing "uploads" directories:
- rsync -auv -e ssh --progress /var/www/html/yoursitesource.org/upload/ username@destinationserverip:/var/www/html/destination/upload/
How to Tar Gzip an Entire Directory (create a tarball for entire directory and all sub-dirs)
- In this example you are creating a backup.tgz file inside migration directory using all of the files and sub-directories from /yoursite.com/
- tar -czvf /var/www/html/migration/backup.tgz /var/www/html/yoursite.com/
You have a large GZIP tar ball, how to download/move a large tar file server to server:
OK, How to "unzip" / un-tar my tar-gzip archive file?
- In this example you created a huge backup.tgz file on a server called serversource1
- Now you want to move it to another server, serverdestination1
- While logged in on serverdestination1 (new server), issue this command:
- scp someusername@serversource1:/var/www/html/migration/backup.tgz /var/www/html/destinationdirectory/
OK, How to "unzip" / un-tar my tar-gzip archive file?
- You've successfully zipped and moved your large gzip file
- The command below will unzip and re-create all of the files and sub-directories from the archive file
- tar -xzf backup.tgz -C /var/www/html/destinationdirectory/
How to dump / create backup for your MySQL Database using mysqldump
- For example, you would like to create a complete database backup file of your vBulletin forum or your Wordpress blog
- mysqldump -h'yourmysqlserverhostname' -u'mysqlusername' -p'mysqlpassword' sourcedbname > backup.sql
- Please note that -h parameter may be optional for some machines and you can remove -h'hostname' entirely from the above command
How to restore MySQL database from dump file
- Earlier, you've created a backup.sql mysql dump file
- Now you want to "restore" this backup file to a new clean database
- Important note: You can't really restore a mysql dump file on top of existing database if the tables already exist, you will have to create a new clean database or "drop" the database entirely. Dropping the database will completely delete all of the tables and content!
- mysql -h'mysqlhostname' -u'mysqlusername' -p'mysqlpassword' destination_databasename < backup.sql
How to merge / synchronize two file folders
- Imagine that you have two slightly different images directories, images_new and images_old
- You want to create just one directory that has all of the up-to-date files
- You want to copy all of the content from images_old into images_new without overwriting anything that has not been updated or modified in any way according to timestamp, not filename.
- rsync -va /var/www/html/images_old/ /var/www/html/images_new
How to find and delete a specific
- In this example you are going to find a filename match for "backup.zip" and then delete it
- $find . -type f -name "backup.zip" -exec rm -f {} \;
How to copy "cp" files from one directory to another, but only new files that do not exist already
- In this example you are trying to copy files from images_old to images_new directories, but do not overwrite any files that exist already.
- In essence you are merging two directories together without overwriting old files
- sudo yes n | cp -i -R /mnt/images_old/* /var/www/sites/images_new/
How to create a symlink, How to create a fake directory alias for easy access
- In this example you are creating a symbolic link between directories
- Really usefull for SVN control also
- In this example your "new_build" directory will replace the "live" directory
- ln -s /home/content//public_html/new_build /home/content/public_html/live
