How do I write a script to execute a few commands?
 

Let's say I wanted to open a file and a folder.

You can do it by placing ; in between the command eg

cd Test; cat Test.txt

Or && if the execution of a command depends on the exit status of the previous one.

Up to how many semicolons can I use?

I'm not sure if there's any limit (I might be wrong). Just tried a line with 60 semicolons and it worked fine (ls ; ls ; .....)

The simplest script is basically just a text file with the commands you want to run stored one-per-line. When one command exits, the next one is executed.

But there's also a whole suite of shell syntax commands that let you do much more if desired. Variables, loops, branching statements, etc.

Here's my usual list of bash resources. Read through the first two at least. The BashGuide covers all the basic concepts in an easy-to-read form, while linuxcommand is more learn-by-doing, taking you step-by-step.

http://mywiki.wooledge.org/BashGuide
http://www.linuxcommand.org/index.php
http://mywiki.wooledge.org/BashFAQ
http://mywiki.wooledge.org/BashPitfalls
http://tldp.org/LDP/Bash-Beginners-G...tml/index.html
http://www.tldp.org/LDP/abs/html/index.html
http://www.gnu.org/software/bash/manual/bashref.html
http://wiki.bash-hackers.org/start
http://ss64.com/bash/