This script replaces the c_rehash perl script from openssl, at least the main functionality of it. From http://man.openbsd.org/SSL_CTX_load_verify_locations

c_rehash.sh

#!/bin/sh
# replaces the c_rehash perl script from openssl.
# by afresh1

rm -f *.[0-9]* *.r[0-9]*
for c in *.pem; do
   [ "$c" = "*.pem" ] && continue
   hash=$(openssl x509 -noout -hash -in "$c")
   if egrep -q -- '-BEGIN( X509 | TRUSTED | )CERTIFICATE-' "$c"; then
     suf=0
     while [ -e $hash.$suf ]; do suf=$(( $suf + 1 )); done
     ln -s "$c" $hash.$suf
   fi
   if egrep -q -- '-BEGIN X509 CRL-' "$c"; then
     suf=0
     while [ -e $hash.r$suf ]; do suf=$(( $suf + 1 )); done
     ln -s "$c" $hash.r$suf
   fi
done