Difference between revisions of "BASH scripting"
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When you initialize the '''shell''', i.e, the interpreter, your computer runs initialization files -- <code>~/.bash_profile</code>, <code>~/.bash_login</code>, and <code>~/.profile</code> (where <code>~/</code> points to your ''home'' directory) -- but we do not recommend changing these files unless you really know what you are doing. | When you initialize the '''shell''', i.e, the interpreter, your computer runs initialization files -- <code>~/.bash_profile</code>, <code>~/.bash_login</code>, and <code>~/.profile</code> (where <code>~/</code> points to your ''home'' directory) -- but we do not recommend changing these files unless you really know what you are doing. | ||
In most cases, you can change the <code>~/.bashrc</code> file, which allows the user to customize the system according to their needs. | In most cases, you can change the <code>~/.bashrc</code> file, which allows the user to customize the system according to their needs. | ||
| + | |||
| + | A '''bash script''' is a text file containing a series of instructions written in the bash language. You can create one by typing the following commands in the terminal: | ||
| + | |||
| + | touch my_first_script.sh | ||
| + | |||
| + | which will generate a modifiable file that you can use to write the instructions to be executed by the shell. You can use the [[Vi]] text editor to write your code; just remember to add to the beginning of the file the following line: | ||
| + | |||
| + | #!/bin/sh | ||
| + | |||
| + | This line tells the interpreter that this is a bash script. You can run your script by telling the interpreter: | ||
| + | |||
| + | bash my_first_script.sh | ||
| + | |||
| + | or you can change the ''permissions'' of the file to make it an ''executable'' by typing: | ||
| + | |||
| + | chmod +x my_first_script.sh | ||
| + | |||
| + | and then running: | ||
| + | |||
| + | ./my_first_script.sh | ||
==Environment Variables== | ==Environment Variables== | ||
Revision as of 11:09, 24 January 2020
Bourne-Again Shell (Bash)
Bash is an acronym for "Bourne-Again Shell", the name of a code interpreter and a high-level programming language, and it is a must-know tool in Computational Chemistry and Biology.
You can use Bash scripting in Unix/Linux computers through a terminal.
When you initialize the shell, i.e, the interpreter, your computer runs initialization files -- ~/.bash_profile, ~/.bash_login, and ~/.profile (where ~/ points to your home directory) -- but we do not recommend changing these files unless you really know what you are doing.
In most cases, you can change the ~/.bashrc file, which allows the user to customize the system according to their needs.
A bash script is a text file containing a series of instructions written in the bash language. You can create one by typing the following commands in the terminal:
touch my_first_script.sh
which will generate a modifiable file that you can use to write the instructions to be executed by the shell. You can use the Vi text editor to write your code; just remember to add to the beginning of the file the following line:
#!/bin/sh
This line tells the interpreter that this is a bash script. You can run your script by telling the interpreter:
bash my_first_script.sh
or you can change the permissions of the file to make it an executable by typing:
chmod +x my_first_script.sh
and then running:
./my_first_script.sh
Environment Variables
Bash allows the user to assign values to variables in the command line, but
