Full bash script check before runing

Question

Trying to implement self syntax checking in bash script test.sh to run syntax check before script will be executed.

error_exit()
{
        echo -e "$1" 1>&2
        exit 1
}
bash -n "$(basename $BASH_SOURCE)"
RESULT=$?
if [ $RESULT == 0 ]; then
  echo "[OK] Test pass"
else
  error_exit "Something is not right :( \n check the sytntax"
fi
starting-script

bash -n , same as bash -x does the job if there are some serous syntax errors but minor errors like:

echo "somthing" && sleep5&&
./test.sh: line 14: sleep5: command not found

are ignored...

is there any way to process a full syntax check plus may be running scrip in some sort of "sandbox mode"/"simulation mode" to catch all possible errors, and return with error if any?

edited In cases when script has to copy some part of the script in tot the remote server, for instance script to install nagios on hundreds of slave(monitored servers) etc. Unfortunately text copying do not always goes smoothly, and errors can be caused by occurred errors while automatically copying script as a text, and it is important to check and end script, if any errors are detected.

Answer 1

As @techraf and @Wice22 pointed out, there is no such thing as a complete check at run-time.

You could create "unit" tests for your bash script though. One framework which helps with it is BATS: https://github.com/sstephenson/bats
Those tests could be run by a CI system on every commit to your git repo, so you would see if you messed up way before those scripts hit production.

However with BATS there is no automatic test for your scripts, but you have to implement every test on your own.

EDIT: In regards to your edit: you could create a md5sum of the script that would be copied, copy them both (remote script and md5sum file) and check remotely if the script is still matching the md5sum.

Answer 2

You might have a look at the ShellCheck project which performs a more thorough validation of shell script syntax; including best practices and potential pitfalls.

However, even ShellCheck won't report the example from your question as incorrect, because there is no syntax error.

You are calling an external command sleep5 which is a syntactically valid action.

Use variables and check if commands exist before calling them, and fail gracefully if they don't.

Answer 3

There is no such thing ans "sandbox mode" in bash as far I'm aware of, no try/catch eater To catch the errors in bash you need to run the script. Try this thread https://stackoverflow.com/questions/22009364/is-there-a-try-catch-command-in-bash You may simulate a bailing outs by using sub shells as shown there, Using that techniques you may be able to stop the script on any point, if "exception" is detected, but this is not a simulation. so it would be something like this:

#!/bin/bash
script_name=$(basename $0)
error_exit() { echo -e "${script_name} file:  ${1:-"Unknown Error"}" 1>&2
exit 1
}
bash -n "$(basename $BASH_SOURCE)"
RESULT=$?
if [ $RESULT == 0 ]; then
  echo $" ${green}[OK] Test pass${reset} "
else
  error_exit "syntax error detected"
fi
echo "Check pass ok"

bash -e <<TRY
  echo "" && sleep5
  echo"and_somthing else"
  echo"and_some_more stuff"
  echo"and some_more"
TRY
if [ $? -ne 0 ]; then
  error_exit "error detected"
fi
echo "continuing if all goes well"