Question

Ok so I was wondering if it is possible to save like a variable in bash. I am writing a script where you build like farms and mines and I was just wondering if it is possible to bring back those variables even after I stopped the program and then got back on. So lets say I have built 4 farms farms would be farm=4, can I bring this variable back somehow? I know how to make a page that you can make a high scores list on (Which I did for a guessing game.), but this I don’t know if it is possible in bash.

Answer 1

You can save all needed variables in a file (using here-doc):

cat<<EOF>/path/to/file
var1="$var1"
var2="$var2"
EOF

and to recreate your previous environment :

source /path/to/file

or

. /path/to/file

EXPLANATIONS

• the place where to put the here-doc depends of your code, can be the last lines if you don’t have to save variables in loops by example
• the place to put the source command is the top of your script after the shebang

Help said :

$ LANG=C help source

source: source filename [arguments]
Execute commands from a file in the current shell.

Read and execute commands from FILENAME in the current shell.  The
entries in $PATH are used to find the directory containing FILENAME.
If any ARGUMENTS are supplied, they become the positional parameters
when FILENAME is executed.

Exit Status:
Returns the status of the last command executed in FILENAME; fails if
FILENAME cannot be read.

NOTE

if you want for some reasons to dynamically generate the files with pattern matching on variable names :

• by suffix : printf '%q\n' $(set | grep "suffix=") > save_file
• by prefix : printf '%q\n' $(set | grep "^prefix") > save_file

Thanks gniourf_gniourf for printf trick.