Linux Command Line: Bash CatĬat is one of the most frequently used commands in Unix operating systems.Ĭat is used to read a file sequentially and print it to the standard output. To avoid that use: chmod u+x myBashScript.shĪnd then execute the script. It is due to the permissions set on the file. Sometimes the script won’t be executed, and the above command will return an error. The second line is the command we want to use, echo, followed by what we want to print which is “Hello World”. The first indicates what interpreter to use to run the file (in this case, bash). Then you could run the script like so: For make file executable you should call this command under sudo chmod +x “filename”./myBashScript.sh scriptname.extension, it will look at the top line to find out the interpreter, whereas, running the script as bash scriptname.sh, first line is ignored. Though it is only executed if you run your script as an executable. #! is often referred to as a “hash-bang”, “she-bang” or “sha-bang”. Adding #!/bin/bash as the first line of your script, tells the OS to invoke the specified shell to execute the commands that follow in the script. This is the standard location of the Bourne shell on just about every Unix system. The first line tells Unix that the file is to be executed by /bin/bash. That is because it is a convention to let the interactive shell know what kind of interpreter to run for the program that follows. Why did we use #!/bin/bash at the beginning of the script file? It is a special directive which Unix treats differently. It’s worth noting that first line of the script starts with #!. Say you had a bash script with the following contents: #!/bin/bash sh file, and run them from the command line. You can also put all of your bash commands into a. Open up your terminal, and write the following line (everything after the $ sign): echo "Hello world!"Īs you can see, we used the echo command to print the string “Hello world!” to the terminal. Let’s consider a simple hello world example. You can start using bash on most Linux and OS X operating systems by opening up a terminal. Using bash on the command line (Linux, OS X)
You can read more about bash here, via the GNU Documentation, and via the tldp guide. Adjusting the volume of the operating system.Many things that can be done Linux operating system can be done via command line. It’s the most widely used shell packaged by default for most Linux distributions, and a successor for the Korn shell (ksh) and the C shell (csh). A shell is simply a macro processor that executes commands. What is Bash?īash (short for Bourne Again SHell) is a Unix shell, and a command language interpreter. This tutorial will show you some of the key Linux command line technologies and introduce you to the Bash scripting language. Welcome to our ultimate guide to the Linux Command Line.
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