i have a script that reads a file line by line
the code is
FILE=commands.txt
while read CMD; do
echo "$CMD"
done < "$FILE"
This code is stored in a script file vxm_alarm.sh
In Korn shell, this loop works perfectly, when i run the command vxm_alarm.sh. In bash however i get the following error
vxm_alarm.sh: syntax error at line 4: `done' unexpected
In Bash I'm executing the script using the command sh vxm_alarm.sh. what am i doing wrong? And why can't we execute a script simply by doing this in bash
chmod +x filename.sh
filename.sh
Your code works on my machine using GNU bash 4.1.5
Try adding a shebang to the top:
#!/bin/sh
FILE=commands.txt
while read CMD; do
echo "$CMD"
done < "$FILE"
If you run sh vxm_alarm.sh you are most likely not running Bash. Try sh --version - If you get anything other than a version string, it's not Bash. Try running bash vxm_alarm.sh instead.
To be able to run a script without a path before it it has to be in one of the directories listed in the PATH variable. For example, if
echo "$PATH"
prints
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
you can put filename.sh in /usr/local/sbin, /usr/local/bin, /usr/sbin, /usr/bin, /sbin or /bin and run it as simply filename.sh. If you want your script to be run from a directory not in the path, you have three choices:
Modify $PATH to include the directory where the script resides.
Run it with a relative or absolute path.
Create an alias or function pointing to the relative or absolute path.
I'd like to answer this part of your question:
why can't we execute a script simply by doing this in bash
chmod +x filename.sh
filename.sh
As others already pointed out in part, there are several things required for that to work:
execution rights (You ensured that with your chmod command)
the shebang, so the system knows what shell/interpreter to use
#!/bin/bash
(it is important to say bash if you want bash and not sh)
make sure the command is found. This is the case when its directory is found in PATH. However what you'd rather do in this case is specify the directory. For the current directory you can do it like this
./name-of-the-script
In contrast to DOS and (IIRC) the various Windows Command line interfaces, Unix systems usually don't have the current directory on the PATH. It is possible to add it, but discouraged due to severe implications on security.
Related
I'm trying to run a CLI tool in Linux (Mint) which allows me to edit subtitles. It is named subedit: github link. In order to run it, I've added executable permission with chmod +x and added it to the path in bash. However, when I run it, I get the following error message:
bash: /home/main/Documents/shellTools/subedit/subedit: /usr/bin/bash: bad interpreter: No such file or directory
I'm not very experienced with external bash programs and forgot to do something that would be obvious in hindsight.
When I do echo $PATH this is the output:
/home/main/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/home/main/Documents/shellTools/subedit/
Could somebody please help?
Assuming bash is installed, (it usually is), change the first line of subedit from:
#!/usr/bin/bash
to:
#!/bin/bash
Or if one would prefer not to edit subedit, try this one-liner covering what Al-waleed Shihadeh suggested:
ln -s "$(which bash)" /usr/bin/bash
It seems that you don't have bash installed, you can verify that by running
which bash
if the above command returns "bash not found", then you need to install it.
In case the above command returns a path, you can use the below command to add a symlink to the expected path
ln -s $(path from the above command) /usr/bin/bash
Use the command termux-chroot ONCE!
If you want to always run at the start of a session, be sure to check if it was never run before.
if [ -z $CHROOT ]; then
CHROOT=1
termux-chroot
fi
I have a shell script with some functionalities. I want to convert it to an executable file. Any idea if this is possible?
Thanks
Add the following line at the very top of your script:
#!/bin/sh
This is known as a shebang. It indicates which program to invoke the shell script with when you execute it. You could change it to anything. Eg, to run a zsh script you would use #!/bin/zsh, which is the path to the zsh interpreter on my machine.
Then you need to mark the file as executable using chmod. You can do this as follows:
chmod +x myscript
You can now run the script like this:
/full/path/to/myscript
Or, if you're in the directory the script is in:
./myscript
The '.' expands to the path of your current working directory.
If you want to be able to run the script from anywhere, stick it somewhere in your path. Eg.
mv myscript /usr/bin
You can now run the script from anywhere by typing in just the name.
In the following script (saved as script.sh):
#!/bin/sh
cd $MY_PYTHON_WORKING_DIRECTORY
python script1.py
python script2.py
Then, when I try to run the command script.sh in my bash shell, I got the error bash: script.sh: command not found. Why does this not work as expected? If the first line of any scripts start by #! prefix, then the following path on the line is interpreted as a command, right? For your information, even if I changed my first line to #!/bin/bash, the same error still occurred. If I run the script as either sh script.sh or bash script.sh, then the script ran as expected.
Is there any way to run the script by just hitting script.sh?
One more question, between sh and bash, which should I use? I'm on OS X 10.8 and my default shell is currently set bash, but I wonder which one to use going forward.
Thanks.
First, make the script executable:
chmod u+x script.sh
Second, your current directory is not in your $PATH. Therefore, you have to run the script with a path (relative is enough):
./script.sh
I've just begun learning Unix and have so far encountered two elementary though difficult to resolve problems:
When I set HOME='' in a shell script to a designated directory, the current directory no longer seems to be recognized. That is, 'cd ~/' spits out the message: 'no such file or directory' message. Although, curiously enough, if aliases assignments are made within the script, a source call seems to activated them nonetheless. How come?
Ex:
$ more .profile
HOME="~/Documents/Basics/Unix/Unix_and_Perl_course"
cd $HOME
[...]
$ source .profile
-bash: cd: ~/Documents/Basics/Unix/Unix_and_Perl_course: No such file or directory
When I created a simple shell script via nano ('hello.sh'), I can't seem to execute it simply by typing 'hello.sh' in the terminal. This issue fails to resolve even after I 'chmod +x' the file. What's the problem?
Ex:
$ more hello.sh
# my first Unix shell script
echo "Hello World"
$ hello.sh
bash: hello.sh: command not found
Thanks!
You also don't want to 'overload' $HOME, the default location for HOME is always your home directory. If you goof with that, lots of things will break.
As far as hello.sh - thats because you don't have '.' in your $PATH. (Which is a good thing)
Try:
./hello.sh
If it says it can't execute
chmod 755 hello.sh
./hello.sh
~ = $HOME
. (pwd) is not in $PATH
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.