What is ACL in Linux?

Access control list (ACL) provides an additional, more flexible permission mechanism for file systems. It is designed to assist with UNIX file permissions. ACL allows you to give permissions for any user or group to any disc resource.
A.

What is the meaning of chmod 777?

In short, “chmod 777means making the file readable, writable and executable by everyone. chmod 775 /path/to/file. Hopefully, this article can help you understand better about the file permissions in Unix system and the origin of the magical number “777”.
  • How do you run a script in Linux?

    The way professionals do it
    1. Open Applications -> Accessories -> Terminal.
    2. Find where the .sh file. Use the ls and cd commands. ls will list the files and folders in the current folder. Give it a try: type "ls" and press Enter.
    3. Run the .sh file. Once you can see for example script1.sh with ls run this: ./script.sh.
  • How do I run a Python script in Linux?

    Linux (advanced)[edit]
    1. save your hello.py program in the ~/pythonpractice folder.
    2. Open up the terminal program.
    3. Type cd ~/pythonpractice to change directory to your pythonpractice folder, and hit Enter.
    4. Type chmod a+x hello.py to tell Linux that it is an executable program.
    5. Type ./hello.py to run your program!
  • How do I run a bash script?

    These are some of the pre-requisites of using directly the script name:
    1. Add the sha-bang {#!/bin/bash) line at the very top.
    2. Using chmod u+x scriptname make the script executable.
    3. Place the script under /usr/local/bin folder.
    4. Run the script using just the name of the script.
B.

What is meant by file permissions?

Each octal digit is the sum of 4 if read permission is granted, 2 if write permission is granted and 1 if execute permission is granted. Here are the most commonly needed permissions: 755 means you can do anything with the file or directory, and other users can read and execute it but not alter it.
  • What is the Execute permission?

    Basically it means you can tell the operating system to run the code in the file. For example, if the file was a binary executable, write access would allow you to modify it, read access would allow you to view it, but without execute permissions you would not be able to run the program.
  • What is the use of umask in Linux?

    On Linux and other Unix-like operating systems, new files are created with a default set of permissions. Specifically, a new file's permissions may be restricted in a specific way by applying a permissions "mask" called the umask. The umask command is used to set this mask, or to show you its current value.
  • What is the use of Umask?

    The user file-creation mode mask (umask) is use to determine the file permission for newly created files. It can be used to control the default file permission for new files. It is a four-digit octal number. A umask can be set or expressed using: Symbolic values.

Updated: 2nd October 2019

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