[makefile] Make: how to continue after a command fails?

The command $ make all gives errors such as rm: cannot remove '.lambda': No such file or directory so it stops. I want it to ignore the rm-not-found-errors. How can I force-make?

Makefile

all:
        make clean
        make .lambda
        make .lambda_t
        make .activity
        make .activity_t_lambda
clean:
        rm .lambda .lambda_t .activity .activity_t_lambda

.lambda:
        awk '{printf "%.4f \n", log(2)/log(2.71828183)/$$1}' t_year > .lambda

.lambda_t:
        paste .lambda t_year > .lambda_t

.activity:
        awk '{printf "%.4f \n", $$1*2.71828183^(-$$1*$$2)}' .lambda_t > .activity

.activity_t_lambda:
        paste .activity t_year .lambda  | sed -e 's@\t@\t\&\t@g' -e 's@$$@\t\\\\@g' | tee > .activity_t_lambda > ../RESULTS/currentActivity.tex

make -k (or --keep-going on gnumake) will do what you are asking for, I think.

You really ought to find the del or rm line that is failing and add a -f to it to keep that error from happening to others though.

Put an -f option in your rm command.

rm -f .lambda .lambda_t .activity .activity_t_lambda

Change clean to

rm -f .lambda .lambda_t .activity .activity_t_lambda

I.e. don't prompt for remove; don't complain if file doesn't exist.

Change your clean so rm will not complain:

clean:
    rm -f .lambda .lambda_t .activity .activity_t_lambda

Return successfully by blocking rm's returncode behind a pipe with the true command, which always returns 0 (success)

rm file | true

To get make to actually ignore errors on a single line, you can simply suffix it with ; true, setting the return value to 0. For example:

rm .lambda .lambda_t .activity .activity_t_lambda 2>/dev/null; true

This will redirect stderr output to null, and follow the command with true (which always returns 0, causing make to believe the command succeeded regardless of what actually happened), allowing program flow to continue.