providing a shell script with parameters from a file

[Maciej Szewczykowski]

hello all.
got a question. i've written a script which contains several variables. because i'd like to run a script each time with different variables values, the most convenient solution seems to be storing the values in a text file. is it possible that a script takes values for it's variables from a file (e.g. using '<' operator)?
thank you in advance.

[Bill McNAMARA_1]

why don't you source the file depending on the arguments supplied:

ie

./script -op
sources file operator.env
and
./script -ad
sources file admin.env

where admin.env contains
export VARIABLE1=one
export VARIABLE2=two

etc

[Stefan Farrelly]

You store variables into a plain file like this;

VAR1=
STRING1=

Then you source this file with .
eg. put these 2 lines above into a file called VARIABLES then from your shell or from a script do;
. ./VARIABLES
This then sources the file and sets up these variables exactly as the are in the file, you can then run your script using these variables.

[Graham Cameron_1]

Yes it's possible, but I wouldn't use "<" here.
Within your script, positional parameters are referenced as $1, $2 etc, with $0 the whole line.
You can run your script based on the contents of textfile, a line at a time, using the following shell command:
--
while read line
do
yourscript.sh "$line"
done < textfile
--
Note the double quotes are needed around "$line" to get the whole line into the script, without them you'd only get the first parameter, not the entire line.
-- Graham

[Maciej Szewczykowski]

dear Graham,
could you please tell me what structure a text file should have?
e.g each variable in separate line?

[Elmar P. Kolkman · Accepted solution]

It depends on the variable values. For instance, if there is a formula for some of them, put that formula in your script instead of creating the parameter file by hand. Or create the parameter file with a script.

If you have a parameter file, make sure it contains all variables for one instance on one line. Then you can do it using the command read.

It will look something like this:
while read parm1 parm2 parm3 ...
do
do_actions
done < param_file

Good luck

[Graham Cameron_1]

To quote the venerable A. Clay Stephenson, "it depends". In fact it's entirely up to you.
There are loads of examples on the system.

For example, have a look at
"/usr/sam/lbin/ioparser.sh" around line 474, where 19 variables are read from a single line.
--
-- Graham