You can run any program within a shell script without user action by supplying the required input for the interactive program.
EOF operator stands for the end of the file. This means that wherever a compiler or an interpreter encounters this operator, it will receive an indication that the file it was reading has ended.
Insert data into the file without using the echo command.
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cat <<EOF > demo.txt
hello world
EOF
You can also use variables here, cat command will execute variables automatically. To avoid execution automatically, use a special character backslash.
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cat <<EOF > demo.sh
Hello, world
whoami=\$HOME
EOF
You can use heredoc to create a template like this. Run the following command as an example.
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cat <<EOF
Usage: <command_name> [option]
Description: Your description.
Options:
-u Update
-h Show the help
-v Get the tool version
-d Show detailed information
EOF