if ! command; then ...; fi

The Solaris shell does not understand this pattern. As a workaround you should use:

if command; then :; else ...; fi

for i in ${DEPENDS}; do ...; done

When this code appears in a BSD Makefile and the DEPENDS variable is empty, the shell gets this code:

for i in ; do ...; done

In the Solaris shell, this is a syntax error. A workaround is:

depends=${DEPENDS:Q}; for i in $$depends; do ...; done

The latter pattern also has the advantage that the DEPENDS string may contain characters like <>&`'". But pay attention to shell wildcards. They are expanded, as the $$depends in the for loop is unquoted.

$(command)

The Solaris shell does not know this alternative to `command`. So just use the backticks.