Question

I’m trying to put a variable into a line that gets put into a file.

The code looks like this:

echo "cd ~/Desktop/BukkitServer/" >> start.command
echo "java -Xms$ramM -Xmx$ramM -jar CraftBukkit.jar" >> start.command
chmod +x start.command

see how i put $ram in the second line? it ends up as

java -XmsM -XmxM -jar CraftBukkit.jar

how do i get it to put whatever $ram is in its proper place?

thanks 🙂

EDIT:

echo 'java -Xms{$ram}M -Xmx{$ram}M -jar craftbukkit.jar' >> start.command

produces java -Xms{$ram}M -Xmx{$ram}M -jar craftbukkit.jar

echo "java -Xms{$ram}M -Xmx{$ram}M -jar craftbukkit.jar" >> start.command

produces java -Xms{120}M -Xmx{120}M -jar craftbukkit.jar

Answer 1

$ is used to mark a variable. With your command you are telling echo to put java -Xms followed by the content of the $ramM variable in the file.

You have to define a value for the variable

ram=128
echo "java -Xms${ram}M"

will produce

java -Xms128M

Note that you will have to use brackets {} to delimit the variable name otherwise the shell will not know where your variable finishes.

If you want to put a literal $ you will have to use single quotes (the shell will not interpret the content of the string).

echo 'java -Xms$ramM'

produces

java -Xms$ramM