Set and Get environmental shell variable using c++

Set and Get environmental shell variable using c++

Environment variables in the Bash shell can be accessed or set using a C++ program. This is facilitated by the getnenv() and putenv() functions defined in the C/C++ stdlib.h library. Environmental variable expansion is a great feature of a Linux shell as it enables programmers and users to rely on the environment settings of each user separately. C++ getenv() will read all exported environmental variables and putenv() will set existing or create new variables.

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How to integrate dialog boxes in shell scripts with Whiptail

How to integrate dialog boxes in shell scripts with Whiptail

The ability to create secure shell scripts is essential not only for system administrators, but also for users who wants to automate repetitive tasks. Sometimes, from our shell scripts, we need to provide the user with some kind of information, ask him/her to provide some input, choose from a set of alternatives, or just ask for his/her confirmation before performing a potentially dangerous operation. All those actions, can be performed from the command line, of course, but to make our scripts more user-friendly, we can use of Whiptail to customize and display textual widgets.

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Example of simple bash script ftp client

Example of simple bash script ftp client

If you need to use FTP to upload some files to a server every so often and want to save yourself some time, you can make a simple Bash script to transfer the files quickly. Rather than entering the username, password, and directory manually, we can get our Bash script to do this tedious legwork for us. In this tutorial, you will see an example script to make FTP transfers a cinch on a Linux system.

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List of exit codes on Linux

List of exit codes on Linux

When a script or process exits or is terminated by some other means, it will have an exit code, which gives some indication about how or why the script or process ended. For example, an exit code of 0 means that the process exited without error – in other words, it completed its task and exited as expected. On the other hand, an exit code of 1 means that the process encountered some kind of error upon exiting.

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Using the mv, rename, and mmv commands to rename files between uppercase and lowercase on Linux

Rename all file names from uppercase to lowercase characters

As a Linux user, you’re likely already familiar with using the mv command to rename a file on a Linux system. The task becomes a little more difficult when you need to rename multiple files at the same time on Linux.

One of the most common batch renaming jobs that are performed is to change all file names to lowercase letters. There are several different ways to do this on Linux. One way is with the native mv utility and a bit of Bash scripting, and the other methods involve the rename and mmv tools, which may or may not already be installed on your Linux distro by default.

In this guide, we’ll go over various command line examples to rename all files from uppercase to lowercase letters on Linux. Some commands will work only for files, some for directories, and some commands work recursively. Take a look at all the different examples below to decide which command(s) to use that would best suit your needs.

In this tutorial you will learn:

  • How to rename all files from uppercase to lowercase using mv, rename, or mmv commands
  • How to install rename and mmv on major Linux distros

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