Create an executable file in linux

Creating executable files in Linux

One thing I plan to be doing is writing (painfully simple) Perl scripts, and I’d like to be able to run them without explicitly calling Perl from the terminal. I appreciate that, to do this, I need to grant them execute permissions. Doing this with chmod is easy enough, but it also seems like a slightly laborious extra step. What I would like is one of two things: Firstly, is there a way to set the execute flag when saving a file? Currently I’m experimenting with gedit and geany, but would be willing to switch to a similarly- (or better-) featured editor if it had this capability. Failing that, is there a way to declare that all files created in a particular directory should have execute permissions? My umask is set to 022, which should be OK, as far as I understand, but it would appear that the files are created as text files (with 666 default permissions) rather than executable files (with 777 default permissions). Perhaps I’m just being lazy, but I figure there must be a more convenient way than chmodding every single script one creates.

You have to print the output of every file. You have to import the right libraries of every file. This seems like another step in the process of programming, and one that is dangerous to circumvent.

5 Answers 5

This should return something like

Then in the first line of your script add:

Then you can execute the file

There may be some issues with the PATH, so you may want to change that as well .

Thanks, but that’s not quite my problem. I’ve already gotten into the habit of starting my scripts with #!/usr/bin/perl. I can run scripts fine once I’ve given them executable permissions; I was just looking for a simpler way of doing so.

May I recommend #!/usr/bin/env perl instead? The env program basically finds the argument given (in this case, «perl») on the PATH and runs that. It’s useful when you’re sending scripts to other people — for example, I use a Mac, and Perl is located in /opt/local/bin.

No need to hack your editor, or switch editors.

Instead we can come up with a script to watch your development directories and chmod files as they’re created. This is what I’ve done in the attached bash script. You probably want to read through the comments and edit the ‘config’ section as fits your needs, then I would suggest putting it in your $HOME/bin/ directory and adding its execution to your $HOME/.login or similar file. Or you can just run it from the terminal.

This script does require inotifywait, which comes in the inotify-tools package on Ubuntu,

sudo apt-get install inotify-tools 

Suggestions/edits/improvements are welcome.

#!/usr/bin/env bash # --- usage --- # # Depends: 'inotifywait' available in inotify-tools on Ubuntu # # Edit the 'config' section below to reflect your working directory, WORK_DIR, # and your watched directories, WATCH_DIR. Each directory in WATCH_DIR will # be logged by inotify and this script will 'chmod +x' any new files created # therein. If SUBDIRS is 'TRUE' this script will watch WATCH_DIRS recursively. # I recommend adding this script to your $HOME/.login or similar to have it # run whenever you log into a shell, eg 'echo "watchdirs.sh &" >> ~/.login'. # This script will only allow one instance of itself to run at a time. # --- config --- # WORK_DIR="$HOME/path/to/devel" # top working directory (for cleanliness?) WATCH_DIRS=" \ $WORK_DIR/dirA \ $WORK_DIR/dirC \ " # list of directories to watch SUBDIRS="TRUE" # watch subdirectories too NOTIFY_ARGS="-e create -q" # watch for create events, non-verbose # --- script starts here --- # # probably don't need to edit beyond this point # kill all previous instances of myself SCRIPT="bash.*`basename $0`" MATCHES=`ps ax | egrep $SCRIPT | grep -v grep | awk '' | grep -v $$` kill $MATCHES >& /dev/null # set recursive notifications (for subdirectories) if [ "$SUBDIRS" = "TRUE" ] ; then RECURSE="-r" else RECURSE="" fi while true ; do # grab an event EVENT=`inotifywait $RECURSE $NOTIFY_ARGS $WATCH_DIRS` # parse the event into DIR, TAGS, FILE OLDIFS=$IFS ; IFS=" " ; set -- $EVENT E_DIR=$1 E_TAGS=$2 E_FILE=$3 IFS=$OLDIFS # skip if it's not a file event or already executable (unlikely) if [ ! -f "$E_DIR$E_FILE" ] || [ -x "$E_DIR$E_FILE" ] ; then continue fi # set file executable chmod +x $E_DIR$E_FILE done 

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How to Make a File Executable in Linux terminal?

New to Linux command line and wondering how to make a bash script or some other file executable? Here’s how to do it.

Each file that is in a POSIX-compatible file system (Ext4, Btrfs, XFS, JFS etc) has «mode bits» assigned to itself.

To make a file executable in Linux, the executable mode bit needs to be enabled.

To set the executable mode bit, the chmod command is used like this:

With that, you can execute said file from the terminal:

That was the quick summary. Let’s see things a bit in detail.

Make a file executable in Linux

There are several ways you can make a file executable in Linux. The most common methods involve using the chmod command, in different ways.

To check if you can execute a file, use the -l flag with ls command.

$ ls -l lhb.txt -rw-r--r-- 1 pratham staff 0 Mar 10 20:49 lhb.txt

In the first column, -rw-r—r— represents that the owner can read and write, users from the group can only read and everyone else can only read the file.

Note the lack of x from the permission symbols. This means that lhb.txt is not executable.

I highly recommend reading about Linux file permissions and brushing up your basics to better understand these commands.

Method 1: Make file executable for everyone

The first method, and the most straightforward one, is to make a file executable using the following command:

The x flag is to set or unset the executable permission of a file. And using + sign before x means we want to set it as an executable file.

This will make the file executable for the owner, group and everyone else. Anyone on the system, will be able to execute it as well.

$ ls -l lhb.txt -rw-r--r-- 1 pratham staff 0 Mar 10 20:49 lhb.txt $ chmod +x lhb.txt $ ls -l lhb.txt -rwxr-xr-x 1 pratham staff 0 Mar 10 20:49 lhb.txt

As you can see now, everyone, the owner, group and others have the executable x bit set. This means everyone can execute this file now.

Method 2: Make file executable only for certain user or group

If you do not want to make everyone able to execute a file, you should specify classes before adding/removing file permissions.

The available classes are:

• u : permissions for owner/user
• g : permissions for group
• o : permissions for others
• a : permissions for everyone

When you specify a class, the syntax is mostly similar to the one you saw in the first method.

This means, if I want to make the file executable in a manner such that only the owner of the file can execute it, and no one else, then I should use the following command:

$ ls -l lhb.txt -rw-r--r-- 1 pratham staff 0 Mar 10 20:49 lhb.txt $ chmod u+x lhb.txt $ ls -l lhb.txt -rwxr--r-- 1 pratham staff 0 Mar 10 20:49 lhb.txt

Similarly, to make it executable for everyone in the group owning that file, I should use the following command:

$ ls -l lhb.txt -rw-r--r-- 1 pratham staff 0 Mar 10 20:49 lhb.txt $ chmod g+x lhb.txt $ ls -l lhb.txt -rw-r-xr-- 1 pratham staff 0 Mar 10 20:49 lhb.txt

When you specify the a class, it is almost as if you did not specify any. Let’s have a look.

$ ls -l lhb.txt -rw-r--r-- 1 pratham staff 0 Mar 10 20:49 lhb.txt $ chmod +x lhb.txt $ ls -l lhb.txt -rwxr-xr-x 1 pratham staff 0 Mar 10 20:49 lhb.txt $ chmod 644 lhb.txt #reset permissions $ chmod a+x lhb.txt $ ls -l lhb.txt -rwxr-xr-x 1 pratham staff 0 Mar 10 20:49 lhb.txt

These commands might appear differently, but they have the same outcome.

Method 3: Use the octal numbers

If you follow the first method, you only enable the executable flag of a file by doing a +x , making it such that anyone can execute it.

But, sometimes you might not want everyone to execute a file, maybe it should need some privileges. In that case, you can specify the full set of permissions.

That is usually done by either providing an octal value or a symbolic value to enable file permissions.

This allows you to have a more granular control over how the flags are set. Below is the syntax for using octal values with chmod command:

If you are not good with numbers, you can use an online chmod calculator, which helps you generate correct octal values and thus avoid using the wrong value and messing up file permissions.

Say, I want to make the file executable only for the owner and group, I need to know its current permissions first, and add the executable bits to it on top of it using [chmod-calculator].

$ ls -l lhb.txt -rw-r--r-- 1 pratham staff 0 Mar 10 20:49 lhb.txt $ chmod 754 lhb.txt $ ls -l lhb.txt -rwxr-xr-- 1 pratham staff 0 Mar 10 20:49 lhb.txt

As you can see, only the owner and group can execute the file.

Conclusion

This article covers making a file executable in a Linux system. It mainly focused on the different ways to use the chmod command. If you want to know more about it, we have a few examples on how to use the chmod command.

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How to Make a File Executable in Linux

Making bash script files executable is an efficient way to run your bash programs because by default the scripts are not executable. This is useful mainly for system administrators, as they need to develop several bash scripts daily to automate their tasks. For example, you might wish to run bash scripts to back up your work or log certain events on your server. So this article will guide you on how you can make your bash scripts executable, and for that, there are two main ways:

• Make a bash file executable using the CHMOD command
• Make a bash file executable using file properties

How to make a file executable using the chmod command

The “chmod” command stands for change mode, and this command can be used to make changes in the file permissions, such as you can make a file writable, readable, and executable. To see these permissions for any file, first, let’s create a bash script file in nano editor:

Then we have written some text and saved the file as shown below:

echo ”This is a test file to make it executable.”

Use the below-mentioned command to check whether the file is executable or not:

In the above image, the letter ‘r’ shows that the file is readable, and ‘w’ shows that the file is writeable and ‘x’ shows that the file is executable, which is currently missing on the above output, and that means you cannot execute this file for now. To verify this, you can execute this file by following the general syntax shown below.

As you can see, it shows an error after trying to execute the text file, and this is where the chmod command comes in handy. To make this file executable, all you need to do is to follow the general syntax shown below:

In the above image, ‘u+x’ shows that you are giving permission to the user to execute a specific file, and you can see that it added a letter ‘x’ in the image and after that, you need to run this bash file by typing.

It can be seen that the content of the bash file is now executed without any error.

How to make a file executable using file properties

You can also make a file executable by right-clicking on the bash file and selecting its ‘Properties’ as shown below:

The next step is to select the ‘Permissions’ tab and then check the option of ‘Allow executing file as program’.

This will also allow you to execute the bash file for which you have selected this option, upon double clicking the file, you will get the prompt as shown below:

You can either get output in the terminal or directly run the script for the desired result.

Conclusion

Making a bash script executable allows you to execute your bash scripts without having to type bash in the terminal. This is especially useful for system administrators, who need to write several bash scripts every day to automate their jobs. So in this article, we have taught you how you can make any bash file executable, and there are two ways for doing this. One is by using the “chmod” command, and the other is by using the file properties.

About the author

Taimoor Mohsin

Hi there! I’m an avid writer who loves to help others in finding solutions by writing high-quality content about technology and gaming. In my spare time, I enjoy reading books and watching movies.

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