Tested code, initially creates a single archive file, then splits it:
gzip -c file.orig > file.gz
CHUNKSIZE=1073741824
PARTCNT=$[$(stat -c%s file.gz) / $CHUNKSIZE]
# the remainder is taken care of, for example for
# 1 GiB + 1 bytes PARTCNT is 1 and seq 0 $PARTCNT covers
# all of file
for n in `seq 0 $PARTCNT`
do
dd if=file.gz of=part.$n bs=$CHUNKSIZE skip=$n count=1
done
This variant omits creating a single archive file and goes straight to creating parts:
gzip -c file.orig |
( CHUNKSIZE=1073741824;
i=0;
while true; do
i=$[i+1];
head -c "$CHUNKSIZE" > "part.$i";
[ "$CHUNKSIZE" -eq $(stat -c%s "part.$i") ] || break;
done; )
In this variant, if the archive's file size is divisible by $CHUNKSIZE, then the last partial file will have file size 0 bytes.