How do I execute a bash script in Terminal?

I have a bash script like:

#!/bin/bash

echo Hello world!

How do I execute this in Terminal?

Yet another way to execute it (this time without setting execute permissions):

bash /path/to/scriptname

$prompt: /path/to/script and hit enter. Note you need to make sure the script has execute permissions.

cd to the directory that contains the script, or put it in a bin folder that is in your $PATH

then type

./scriptname.sh

if in the same directory or

scriptname.sh

if it's in the bin folder.

You could do:
sh scriptname.sh

This is an old thread, but I happened across it and I'm surprised nobody has put up a complete answer yet. So here goes...

The Executing a Command Line Script Tutorial!

Q: How do I execute this in Terminal?

> The answer is below, but first ... if you are asking this question, here are a few other tidbits to help you on your way:

Confusions and Conflicts:

The Path

• Understanding The Path (added by tripleee for completeness) is important. The "path" sounds like a Zen-like hacker koan or something, but it is simply a list of directories (folders) that are searched automatically when an unknown command is typed in at the command prompt. Some commands, like ls may be built-in's, but most commands are actually separate small programs. (This is where the "Zen of Unix" comes in ... "(i) Make each program do one thing well.")

Extensions

• Unlike the old DOS command prompts that a lot of people remember, you do not need an 'extension' (like .sh or .py or anything else), but it helps to keep track of things. It is really only there for humans to use as a reference and most command lines and programs will not care in the least. It won't hurt. If the script name contains an extension, however, you must use it. It is part of the filename.

Changing directories

• You do not need to be in any certain directory at all for any reason. But if the directory is not on the path (type echo $PATH to see), then you must include it. If you want to run a script from the current directory, use ./ before it. This ./ thing means 'here in the current directory.'

Typing the program name

• You do not need to type out the name of the program that runs the file (BASH or Python or whatever) unless you want to. It won't hurt, but there are a few times when you may get slightly different results.

SUDO

• You do not need sudo to do any of this. This command is reserved for running commands as another user or a 'root' (administrator) user. Running scripts with sudo allows much greater danger of screwing things up. So if you don't know the exact reason for using sudo, don't use it. Great post here.

Script location ...

• A good place to put your scripts is in your ~/bin folder.
• You can get there by typing

# A good place to put your scripts is in your ~/bin folder.

> cd ~/bin # or cd $HOME/bin

> ls -l

> You will see a listing with owners and permissions. You will notice that you 'own' all of the files in this directory. You have full control over this directory and nobody else can easily modify it.

If it does not exist, you can create one:

> mkdir -p ~/bin && cd ~/bin
> pwd

/Users/Userxxxx/bin

---

A: To "execute this script" from the terminal on a Unix/Linux type system, you have to do three things:

1. Tell the system the location of the script. (pick one)

# type the name of the script with the full path
> /path/to/script.sh

# execute the script from the directory it is in
> ./script.sh

# place the script in a directory that is on the PATH
> script.sh

# ... to see the list of directories in the path, use:
> echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

# ... or for a list that is easier to read:
> echo -e ${PATH//:/\\n}
# or
> printf "%b" "${PATH//:/\\n}"
/usr/local/sbin
/usr/local/bin
/usr/sbin
/usr/bin
/sbin
/bin

2. Tell the system that the script has permission to execute. (pick one)

# set the 'execute' permissions on the script
> chmod +x /path/to/script.sh

# using specific permissions instead
# FYI, this makes these scripts inaccessible by ANYONE but an administrator
> chmod 700 /path/to/script.sh

# set all files in your script directory to execute permissions
> chmod +x ~/bin/*

There is a great discussion of permissions with a cool chart here.

3. Tell the system the type of script. (pick one)

• Type the name of the program before the script. (Note: when using this method, the execute(chmod thing above) is not required

> bash /path/to/script.sh
... 

> php /path/to/script.php
... 

> python3 /path/to/script.py
...

• Use a shebang, which I see you have (#!/bin/bash) in your example. If you have that as the first line of your script, the system will use that program to execute the script. No need for typing programs or using extensions.
• Use a "portable" shebang. You can also have the system choose the version of the program that is first in the PATH by using #!/usr/bin/env followed by the program name (e.g. #!/usr/bin/env bash or #!/usr/bin/env python3). There are pros and cons as thoroughly discussed here.

> Note: This "portable" shebang may not be as portable as it seems. As with anything over 50 years old and steeped in numerous options that never work out quite the way you expect them ... there is a heated debate. The most recent one I saw that is actually quite different from most ideas is the "portable" perl-bang:

#!/bin/sh
exec perl -x "$0" "$@"
#!perl

Firstly you have to make it executable using: chmod +x name_of_your_file_script.

After you made it executable, you can run it using ./same_name_of_your_file_script

Change your directory to where script is located by using cd command

Then type

bash program-name.sh

And yet one more way

. /path/to/script

What is the meaning of the dot?

If you are in a directory or folder where the script file is available then simply change the file permission in executable mode by doing

chmod +x your_filename.sh

After that you will run the script by using the following command.

$ sudo ./your_filename.sh

Above the "." represent the current directory. Note! If you are not in the directory where the bash script file is present then you change the directory where the file is located by using

cd Directory_name/write the complete path

command. Otherwise your script can not run.