How to create an executable for a shell script in Ubuntu? - linux

I have written a simple Shell script named decBright.sh that decreases my screen brightness by a bit every time I run it. However, I do not want to open the terminal and execute bash decBright.sh every single time.
Instead, I want to create some kind of executable file that I can place on my Desktop, which will run my script when it is double-clicked. One answer I found here on the askUbuntu forums did not work for me.
Is there some other way to do it?
I am using Ubuntu 14.04 (Trusty Tahr)

An executable in linux is a file with the executable bit on. Thus you simply modify it with chmod:
chmod +x decBright.sh
Then you can run it with:
./decbright.sh
You can also run it by double-clicking in many graphical linux distributions.
You also better provide a "Shebang": the first line of your script should specify the "interpreter":
#!/bin/bash
Or any other interpreter (at the first line of your file).

Related

Unable to run shell script from Windows batch file

I've been trying to do some scripting, but I can't seem to understand this one error I have.
bash: /test.sh: No such file or directory
Basically, I want to run a script, test.sh using bash with the -c and -l options:
bash -l -c ~/opt/ct/src/test.sh
but this whole line is called from an Windows batch file (.cmd) located in the same directory as test.sh. I'm using 64-bit Cygwin (but I also have MinGW installed). I have ensured that the filepaths point to bash.exe (did a set PATH) and that it is the correct one, as is the shebang. I also did dos2unix on the script.
Any ideas on why? FYI the line I wrote worked perfectly fine in Cygwin.
I found the problem.
I knew I had added the path to MinGW a long time ago in the Windows Path variable. It seems that when I did bash, it was actually running the one from MinGW and not Cygwin (verified using which bash.exe).
I removed the path to MinGW and voila, it worked.
Moral of the story: Never put two paths that point to two identically named program in a Path variable!

Linux version of a .cmd file

I am creating a terminal program and cannot find out what the ending is for Linux. I know in windows it is .cmd. Any help would be great.
Thank you.
Yes, you can remove the .sh at the end and it should work, generally using ./cmd will get it to run. this goes for C programs as well. You do not need to give an extension for the object file, You could then add a path to your bash file and then you can execute it as a normal command.
Look here.
https://stackoverflow.com/a/8779980/2720497
You don't need a file extension on Linux, though typically, people use .sh (sh being short for 'shell').
You can run it one of two ways:
bash myscript.sh
or you can make the script itself executable and run it directly:
chmod a+x myscript.sh # make it executable
./myscript.sh # run it
Linux scripts' first line is typically #!/bin/bash which is the path to the specific shell used to run the script with the second method.

Default file ending in Mac, Linux and Windows to run executable in the shell/terminal

I created executables of a python script (via pyinstaller) for Mac, Windows and Linux. For Linux and Mac, I am running them in the shell since it doesn't have an own interface: just open a shell and type the name of the program.
I am wondering if there is a way to use certain file ending so if the user clicks on the program, it will be automatically executed in the shell or terminal. Alternatively, I would appreciate any other ideas of how to do this.
The way to do this is not to append a certain file ending, but, as pointed out in the comment, make the file executable (chmod +x <file>) and add the magic bytes to the beginning of the file that tell the system how to execute it.
The magic bytes are #! and are followed by the path to executable. So for a python script you would put something like the following at the top of the file:
#!/usr/bin/env python
Okay, now I finally found out the solution to my question. All you have to do to execute the program upon clicking on it in the file browser is to add the ending .command and make it executable
E.g., exampleprogram.command. Clicking on it will execute the program in the shell

What's a .sh file?

So I am not experienced in dealing with a plethora of file types, and I haven't been able to find much info on exactly what .sh files are. Here's what I'm trying to do:
I'm trying to download map data sets which are arranged in tiles that can be downloaded individually: http://daymet.ornl.gov/gridded
In order to download a range of tiles at once, they say to download their script, which eventually leads to daymet-nc-retrieval.sh: https://github.com/daymet/scripts/blob/master/Bash/daymet-nc-retrieval.sh
So, what exactly am I supposed to do with this code? The website doesn't provide further instructions, assuming users know what to do with it. I'm guessing you're supposed to paste the code in to some other unmentioned application for a browser (using Chrome or Firefox in this case)? It almost looks like something that could be pasted in to Firefox/Greasemonkey, but not quite. Just by a quick Google on the file type I haven't been able to get heads or tails on it.
I'm sure there's a simple explanation on what to do with these files out there, but it seems to be buried in plenty of posts where people are already assuming you know what to do with these files. Anyone willing to just simply say what needs to be done from square one after getting to the page with the code to actually implementing it? Thanks.
What is a file with extension .sh?
It is a Bourne shell script. They are used in many variations of UNIX-like operating systems. They have no "language" and are interpreted by your shell (interpreter of terminal commands) or if the first line is in the form
#!/path/to/interpreter
they will use that particular interpreter. Your file has the first line:
#!/bin/bash
and that means that it uses Bourne Again Shell, so called bash. It is for all practical purposes a replacement for good old sh.
Depending upon the interpreter you will have different languages in which the file is written.
Keep in mind, that in UNIX world, it is not the extension of the file that determines what the file is (see "How to execute a shell script" below).
If you come from the world of DOS/Windows, you will be familiar with files that have .bat or .cmd extensions (batch files). They are not similar in content, but are akin in design.
How to execute a shell script
Unlike some unsafe operating systems, *nix does not rely exclusively on extensions to determine what to do with a file. Permissions are also used. This means that if you attempt to run the shell script after downloading it, it will be the same as trying to "run" any text file. The ".sh" extension is there only for your convenience to recognize that file.
You will need to make the file executable. Let's assume that you have downloaded your file as file.sh, you can then run in your terminal:
chmod +x file.sh
chmod is a command for changing file's permissions, +x sets execute permissions (in this case for everybody) and finally you have your file name.
You can also do it in your GUI. Most of the time you can right click on the file and select properties; in XUbuntu the permissions options look like this:
If you do not wish to change the permissions, you can also force the shell to run the command. In the terminal you can run:
bash file.sh
The shell should be the same as in the first line of your script.
How safe is it?
You may find it weird that you must perform another task manually in order to execute a file. But this is partially because of a strong need for security.
Basically when you download and run a bash script, it is the same thing as somebody telling you "run all these commands in sequence on your computer, I promise that the results will be good and safe". Ask yourself if you trust the party that has supplied this file, ask yourself if you are sure that you have downloaded the file from the same place as you thought, maybe even have a glance inside to see if something looks out of place (although that requires that you know something about *nix commands and bash programming).
Unfortunately apart from the warning above I cannot give a step-by-step description of what you should do to prevent evil things from happening with your computer; so just keep in mind that any time you get and run an executable file from someone you're actually saying, "Sure, you can use my computer to do something".
If you open your second link in a browser you'll see the source code:
#!/bin/bash
# Script to download individual .nc files from the ORNL
# Daymet server at: http://daymet.ornl.gov
[...]
# For ranges use {start..end}
# for individul vaules, use: 1 2 3 4
for year in {2002..2003}
do
for tile in {1159..1160}
do wget --limit-rate=3m http://daymet.ornl.gov/thredds/fileServer/allcf/${year}/${tile}_${year}/vp.nc -O ${tile}_${year}_vp.nc
# An example using curl instead of wget
#do curl --limit-rate 3M -o ${tile}_${year}_vp.nc http://daymet.ornl.gov/thredds/fileServer/allcf/${year}/${tile}_${year}/vp.nc
done
done
So it's a bash script. Got Linux?
In any case, the script is nothing but a series of HTTP retrievals. Both wget and curl are available for most operating systems and almost all language have HTTP libraries so it's fairly trivial to rewrite in any other technology. There're also some Windows ports of bash itself (git includes one). Last but not least, Windows 10 now has native support for Linux binaries.
sh files are unix (linux) shell executables files, they are the equivalent (but much more powerful) of bat files on windows.
So you need to run it from a linux console, just typing its name the same you do with bat files on windows.
Typically a .sh file is a shell script which you can execute in a terminal. Specifically, the script you mentioned is a bash script, which you can see if you open the file and look in the first line of the file, which is called the shebang or magic line.
I know this is an old question and I probably won't help, but many Linux distributions(e.g., ubuntu) have a "Live cd/usb" function, so if you really need to run this script, you could try booting your computer into Linux. Just burn a .iso to a flash drive (here's how http://goo.gl/U1wLYA), start your computer with the drive plugged in, and press the F key for boot menu. If you choose "...USB...", you will boot into the OS you just put on the drive.
How do I run .sh scripts?
Give execute permission to your script:
chmod +x /path/to/yourscript.sh
And to run your script:
/path/to/yourscript.sh
Since . refers to the current directory: if yourscript.sh is in the current directory, you can simplify this to:
./yourscript.sh
or with GUI
https://askubuntu.com/questions/38661/how-do-i-run-sh-scripts/38666#38666
https://www.cyberciti.biz/faq/run-execute-sh-shell-script/
open the location in terminal then type these commands
1. chmod +x filename.sh
2. ./filename.sh
that's it

Scripting Linux to install several programs at once

I've been installing step by step video conversion codec and tools for a few hours now, and it is just plan annoying. Is it possible to design a script to load in linux to do all the commands in sequence one after another?
Absolutely. Create a plain text file, put #! /bin/bash at the top, then write all the commands in the file. Save it, "chmod +x yourFile", then run it by calling ./yourFile.
If your installs are a more intricate, I'd need to see an example to say more specifically how to do this as a shell script.

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