命令在终端中运行，但不在bash脚本中运行

Question

I'm new to Linux but i'm doing a tutorial for Antlr4. Recently, I've come into a problem. When I try to set up my Antlr4 project, I run the following commands in a terminal:

antlr4 MyGram.g4
javac *.java
grun MyGram prog test.in
dot -Tpdf test.dot > test.pdf

Everything runs fine and it creates a pdf file showing the parse tree. However, when I put these commands into a bash script called build.sh:

#!/bin/bash

antlr4 MyGram.g4
javac *.java
grun MyGram prog test.in
dot -Tpdf test.dot > test.pdf

and then run the command: ./build.sh and I get the following errors and no pdf file is created:

./build.sh: line 3: antlr4: command not found
javac: file not found: *.java
Usage: javac <options> <source files>
use -help for a list of possible options
./build.sh: line 5: grun: command not found
Error: dot: can't open test.dot

Can anyone please explain the reason why I'm getting these errors ? I'm running Ubuntu 18.04 on VMware Workstation 14 Player.

Answer 1

For some reason, antlr4 and grun are not in your $PATH.

type antlr4 

will show you where it it. Add that to your PATH in your .bashrc or .profile

Answer 2

antlr4 and grun are aliases that you have defined in your command window.

When you run your script, you are in a different environment.

So you should either:

1. define your aliases at the beginning of your script
2. not use aliases in your script

I agree with @Tejas comment: you should use full paths in your script (far easier to maintain)