one-liners

# find all the java files
$(shell find . -name '*.java')

# convert java file into fully qualified name
$(subst /,.,$(patsubst %.java,,$(sources)))
$(subst /,.,$(subst %.java,,$(sources)))

# determine if there are duplicate programs in the path.
$(shell find $(subst :, ,$(PATH)) -name ls)

# A non-caching replacement for wildcard.
file-exists = $(shell test -e $1 && echo $1)

# Generate an output file name.
RELEASE_TAR := mpwm-$(shell date +%F).tar.gz

# Convert dos file path to unix.
drive-letter-to-slash = /$(subst :,,$1)

# Handling file names with spaces

# add version suffix to file
get-release-dir = $(release-path)$(if $(all-release-path),_$(words $(all-release-path)))

# determine if a list has duplicates
$(findstring $(words $(list)) $(words $(sort $(list))))

# determine if a file list contains illegal suffix
$(if $(filter-out $1,$2),$(warning Illegal suffixes in list.))