Ubuntu – Not evaluating an expression when using cat

bash

I have one bash script that is designed to output another bash script. I am using cat. I want to evaluate some of the expressions in output script, but not others.

PROJECT=myproject

cat << EOF > create_dir.sh
#!/usr/bin/env bash

DATE=`date '+%y%m%d-%H%M'`
mkdir $PROJECT/\$DATE
EOF

The resulting create_dir.sh file looks like this:

#!/usr/bin/env bash

DATE=171123-1834

mkdir myproject/$DATE

The result that I want is this:

#!/usr/bin/env bash

DATE=`date '+%y%m%d-%H%M'`

mkdir myproject/$DATE

How can I modify this script so that the expression following DATE= is not evaluated, while at the same time ensuring that $PROJECT is evaluated?

Best Answer

You need to escape the '`' symbols since they mean "execute this code". So that line should look like:

DATE=\`date '+%y%m%d-%H%M'\`

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Ubuntu – Bash Script: catching errors in a block of statements

You could use the trap shell builtin command to have a handler function called if a command has a non-zero exit status. You can pass necessary information, like the line number and the exit status to your error handler function.

Example:

#!/bin/bash

handle_error() {
    echo "FAILED: line $1, exit code $2"
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trap 'handle_error $LINENO $?' ERR 

# your commands here
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How to Run a Shell Script Before Desktop Session Begins

Rather than executing the script before session begins, you can execute it as soon as session begins. For an end user, this does not make difference as scripts would have started executing when you see your session.The steps are as follows.

Create a shell script and provide it necessary permissions.
Open startup applications by searching in dash or your menu, depending on your OS.
Click on Add.
Give a name and add the command, which would be location of your script.You may also add a optional comment.
Click on add, ensure that script is selected and then close the window.

Next time the script would be executed on startup.

Best Answer

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