Go Premium for a chance to win a PS4. Enter to Win

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 368
  • Last Modified:

bash script to expand variables

in a bash script, the user keys in a command with arguments
some of the arguments are variables defined in the bash profile
i need to run the command they enter
How does the script get the information and then does the whole command?

in the bash profile
  export TESTING=/home/programming

in the script, the user keys in: cd $TESTING/penguins

the script needs to: cd /home/programming/penguins

I am running RedHat EL 6.4
0
penguins_rule
Asked:
penguins_rule
1 Solution
 
Gerwin Jansen, EE MVETopic Advisor Commented:
The script inherits the variables from the environment, you are setting the TESTING variable in the bash profile.

In the script you can use variables by using $VARIABLE_NAME or ${VARIABLE_NAME} in your case $TESTING or ${TESTING}

By doing: cd $TESTING/penguins in the script it is in fact doing: cd /home/programming/penguins

So looks OK to me ;)
0
 
simon3270Commented:
Are the users prompted to enter a command, then they type in "cd $TESTING/penguins"?

If so, the command you need is "eval", as in:
echo "Enter your command:"
read cmd
eval $cmd

Open in new window

This is a bit dangerous (they could type in anything!).

I did think that there might be a specific problem with the "cd" command - if the command is run in a subshell, then the "cd" would have no effect, but in the above example it would actually change the directory.
0
 
penguins_ruleAuthor Commented:
in my case, i am using the script to make sure they can only type in certain commands. Otherwise, i agree, it would be dangerous.
0

Featured Post

Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Tackle projects and never again get stuck behind a technical roadblock.
Join Now