16 Really Useful Shell Commands for Web Developers
For me using the shell while developing is an indispensible powerful tool (either through Putty in Windows or using Terminal in Mac OS\Linux). If you have a VPS or a dedicated server there are some great out of the box shell tools which can help you develop faster and smarter.
Below is my top 16 list of shell commands (not in any order of preference) I use when developing. I often find myself using the shell rather than using ftp. Here is the list and reasons anyway!
Before starting with this article
This article assumes basic shell navigation knowledge. If you aren’t familiar with using the cd and su command I recommend doing some google / wikipedia research before experimenting with the commands below.
Introduction
Here is a few bits of information that will help with regard to this article and using the shell in general:
# ./
This means the current directory you are in (which can be checked by using the pwd command)
# ../
This means go down a directory from the one you are currently in e.g.
# cd ../myfolder
The TAB key on your keyboard auto completes file and folder names typed in the shell. So if you are in a directory which has a file called myfile.php you could type myf and then tab and the shell will auto-complete it saving you valuable keystrokes 
.
# *
The (wildcard) symbol for ‘everything’. So for example all files in a directory or all folders in a directory
# -R
This particular option means recursive (go through all sub-folders and files from the present working directory) for alot of file modifcation commands so is noteable for that reason
# man commandname
This always provides the full manual for a command when typed in the shell. Sometimes google or wikipedia can be a bit more accessible for useful command examples.
Short Disclaimer
Some of the commands listed below require use of the root login. As its obligitory to mention in linux related articles like this, be careful when using this login as not paying attention with commands like rm can result in you needing to pay your ISP to restore your server! Installing virtualbox on your computer and then installing linux without a GUI/Desktop is a great way to experiment without risking breaking anything if you’re not feeling confident.
Jump to a Section
- grep – Search inside multiple files fast!
- nano – Easy to use powerful text editor
- pwd – Find out where you are on your server
- ls – List the content of directories
- tar – Extract and backup files
- wget – Download files to your server
- find – Find files based on their name
- rm – Delete files from your server
- mv – Move files on your server
- touch – Create emtpy files
- chmod – Change file permissions
- chown – Change file owner & group
- mkdir – Create directories
- cp – Copy files
- sed – Find & Replace
- unzip – Unzip files
1. grep
Grep is probably my favourite command. Ever needed to find out which file a class is being used but there are hundreds of files in multiple directories? grep will find it (almost instantly in most situations)!
Example use
Navigate to the root directory of the server in Putty or Terminal and run the following command
cd /var/www/vhosts/mydomain.com/httpdocs
grep –r “the string I want to search” ./
The above command will recursively search inside every file from the web space root and the files in all sub-directories.
More info
Type:
man grep
in the shell for more example uses of the grep Command
2. nano
Ok this one’s a bit of a cheat as nano doesn’t always come pre-installed on a vps or dedicated linux server usually, however it is my favourite text editors due to its simplicity, speed and easy search functionality (developers familiar with other text editors should be able to get going with it straight away). There is also a little know about syntax highlighting option although I’ve never used it. http://wiki.linuxhelp.net/index.php/Nano_Syntax_Highlighting
Example use
As I mentioned it’s is often the case that nano isn’t pre-installed on your vps or dedicated server. To install it on one of our Centos/Redhat VPS or Dedicated servers you would do the following:
# su
Switch to the root user
yum install nano
Install nano using Yum. Just say yes to the prompts and it installs in seconds, job done.
Unzip the file myzipfile.zip into the current directory
General Usage
nano myfile.php
Open myfile.php with nano
If you want to create a new file in Nano type the following:
nano mynewfile.txt
As mynewfile.txt doesn’t existing in the present working directory nano will create a new file called mynewfile.txt
Once inside the nano program most commands are ctrl + ‘a key’. So common ones are
Ctrl + X
Exit the program. It will prompt you to save if you haven’t saved the changes you’ve made
Ctrl + W
Search for a string, obviously invaluable for editing code etc
More info
man nano
Type the above in the shell once the program is installed for the nano manual
3. pwd
Stands for present working directory and lets you know where you are folder wise at the present time. Seriously helpful in preventing you doing something silly in the wrong directory (like rm –rf for example ).
Example use
pwd
Just this type this at any time in the shell to be told which directory you’re currently in.
More info
The Wikipedia entry on pwd http://en.wikipedia.org/wiki/Pwd
man pwd
4. ls
Lists the files in the present working directory. Invaluable for seeing what is where and how big files are.
Example use
ls -lash
Shows all files in a folder including hidden files and shows file sizes in human readable form (KB, MB, GB etc)
More info
The Wikipedia entry on ls http://en.wikipedia.org/wiki/Ls
man ls
5. tar
A very useful program for both extracting and creating backup archives of files. If you’ve just downloaded the latest WordPress version in tar.gz format tar is the tool to quickly extract the fileset and start working. Also, very useful and quick for creating a backup of your files.
Example use
tar –xzf latest.tar.gz
Extract latest.tar.gz into the current directory
tar –xzfv latest.tar.gz
Extract latest.tar.gz into the current directory and display what tar is doing as it uncompresses the file.
tar -cf archive.tar myDirectories/
Creates a complete backup called archive.tar of the myDirectories/ folder and all subfolders
tar -cf archive.tar *
Creates a complete backup called archive.tar of the entire present working directory and all sub-directories
More info
man tar
6. wget
Essential for getting files from the web into your webspace. This command is very useful combined with tar and Firefoxes ‘copy link location.’ I’ll give an example with the popular blogging application wordpress
Example use
Visit http://wordpress.org/download/ and right click on the .tar.gz link and select “Copy Link Location” now go to Putty or Terminal and type wget followed by right clicking to paste the download url
wget http://wordpress.org/latest.tar.gz
Downloads the latest wordpress fileset. You’d now want to use the tar command to open up the tar.gz archive into the folder you downloaded to (again checkable using pwd)
tar –xzf latest.tar.gz
This uncompresses the archive ready to install once you’ve chmodded the appropriate files
More info
The Wikipedia entry on wget http://en.wikipedia.org/wiki/Wget
man wget
In the shell for more example uses of the wget Command
7. find
Just like it says on the tin find finds files based on filename, and just like all unix shell tools does it fast .
Example use
cd /www/vhosts/www/mydomain.com/httpdocs/
find –name myfile.php
Unlike grep this command is automatically recursive from the directory you are currently in (to check this see pwd)
More info
Type:
man find
In the shell for more example uses of the find Command
8. mv
Need to move some files from one location to another in the shell? mv does what you need. It is often handy to use a wild card * with this command to move more than one file or the contents of a directory.
Example use
mv /myfolder/folderA /myfolder/folder
mv /myfolder/* /anotherfolder
These are a couple of simple examples. There is much more that can be done with this command if you read the manual as mentioned below
More info
Type:
man mv
In the shell for more example uses of the mv Command
9. touch
Although not that obviously useful, touch creates a completely empty file of your choosing. Where it can come in handy is when a application needs a config.php creating before it can write its config data. Using touch and possibly chmod to make the file writable (see point 5) can achieve this very quickly.
Example use
touch config.php
Creates a new completely empty file called config.php. Good times!
More info
Type:
man touch
In the shell for more example uses of the touch Command
10. chmod
Even if you’ve not been in the shell before you’ve probably know what this one does. Chmod permissions can be set using any ftp client. The main benefit of using the shell to set file permissions is *speed*. This method takes seconds or less compared to chmoding a fileset using ftp and having to put a brew on while you wait. There are some strong arguments for the ftp method due to the whole brew thing, but hey I’m impatient .
Example use
chmod 755 config.php
Give the file config.php 755 chmod permissions
chmod –R 755 *
Recursively chmod every file in the current directory and directory below it to 755
chmod 755 myfolder/
Change the permissions on just the myfolder directory. If you put a –R in there it will do all files and folders below that folder too as shown below
chmod –R 755 myfolder/
More info
The Wikipedia entry on CHMOD permissions http://en.wikipedia.org/wiki/Chmod
man chmod
In the shell for more example uses of the chmod Command
11. chown
Ever had some files that you just can’t delete via ftp ?? This is where chown often comes in very handy. Systems like the e-commerce solution Magento and most CMS systems will create files (usually files uploaded via the CMS control panel) where the user and group permissions are set to user ‘apache’ and group ‘apache’. This means that as your ftp user and group don’t have permission to delete files that belong to apache so they then can’t be removed by ftp. If you do need to remove these files an easy fix is to update the permissions via the shell and this is where the chown command is very useful. With this one command you can change both a files user and group in 1 go.
Example use
chown myuser:mygroup file.php
Change the owner and group of file.php to user myuser and mygroup. If using NuBlue VPS or Dedicated hosting the above command would be (the rest of the examples relate to our hosting):
chown myftpusername:psacln file.php
Give the file file.php ftp user ownership allowing it to be removed via ftp
chmod 755 myfolder/
Change the permissions on just the myfolder directory. If you put a –R in there it will do all files and folders below that folder too as shown below
chmod –R 755 myfolder/
More info
The Wikipedia entry on CHMOD permissions http://en.wikipedia.org/wiki/Chmod
man chown
In the shell for more example uses of the chmod Command
12. mkdir
Makes directories/folders in your webspace (or any where else for that matter), enough said.
Example use
mkdir nameofmyfolder
Creates a directory called nameofmyfolder. Its always handy to use the pwd and ls commands before doing this to confirm you’re in the folder you think you’re in.
mkdir –p /myfolder/myfirstsubfolder/mysecondsubfolder
Create the above folder hierarchy
mkdir folder1 folder2 folder3
Creates 3 directories called folder1 folder2 and folder3 in the current directory you’re in
More info
The Wikipedia entry on mkdir http://en.wikipedia.org/wiki/Mkdir
man mkdir
In the shell for more example uses of the mkdir Command
13. cp
Copies files, obviously very useful.
Example use
cp orginalfile copyoforignafile
Copies originalfile and creates a new file called copyoforiginalfile
cp –R ./myfolder ./mynewfolder
Copy all files and folders within myfolder to mynewfolder
cp ./httpdocs/myfolder/mywebfiles/* /var/www/vhosts/myotherwebsite.com/httpdocs/myotherwebfiles/
Copies the entire contents of mywebfiles into the folder myotherwebfiles in another webspace
More info
The Wikipedia entry on cp http://en.wikipedia.org/wiki/Cp_unix
man cp
In the shell for more example uses of the cp Command
14. sed
Although it certainly doesn’t sound like it this is ‘Find and Replace’ linux style. As with other more complex shell commands it can be difficult to remember so its often handy to copy and paste a sample and adjust for your needs
Example use
sed 's/original text/altered text/g' example.php
Find the string “original text” in example.php and replace with the string “altered text”
sed 's/original text//g' example.php
Delete the text ‘original text’ from the file example.php
More info
The Wikipedia entry on sed http://en.wikipedia.org/wiki/Sed
man sed
In the shell for more example uses of the sed Command
15. rm
Removes files and directories. NB Its possible to seriously damage/destroy your server/vps with this command always make sure you’re in the right directory using pwd before running it.
Example use
rm file.php
Remove the file file.php
rm –rf *
Remove everything in the current directory and all files and folders below it. The ‘f’ in –rf means force which suppresses any deletion warnings so again make sure its correct before you do it as there is no undo.
rm –rf myfolder/
Remove the directory myfolder and all files and subfolders
More info
The Wikipedia entry on rm http://en.wikipedia.org/wiki/Rm_(Unix)
man rm
16. unzip
Handy purely because sometimes a file that you might wget might be in a straight zip format rather than the common tar.gz compression.
Example use
unzip myzipfile.zip
Unzip the file myzipfile.zip into the current directory
More info
man unzip
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