How can I quickly create a large file on a Linux system?
Normally dd command creates a large file but it reads from /dev/zeor and then writes to drive which can take a longer time which you need a very large file.
If you don’t care what should be the contents and just want to add the file quickly you can use fallocate command to do this.
Below command will create 10GB of file in no time. You can modify it as per your needs
# fallocate -l 10GB /justgeek
[[email protected] /]# du -sh justgeek 9.4G justgeek [[email protected] /]#
There are other options you can use for fallocate, you can try help command to explore more.
[[email protected] /]# fallocate --help Usage: fallocate [options] <filename> Preallocate space to, or deallocate space from a file. Options: -c, --collapse-range remove a range from the file -d, --dig-holes detect zeroes and replace with holes -i, --insert-range insert a hole at range, shifting existing data -l, --length <num> length for range operations, in bytes -n, --keep-size maintain the apparent size of the file -o, --offset <num> offset for range operations, in bytes -p, --punch-hole replace a range with a hole (implies -n) -z, --zero-range zero and ensure allocation of a range -x, --posix use posix_fallocate(3) instead of fallocate(2) -v, --verbose verbose mode -h, --help display this help -V, --version display version For more details see fallocate(1). [[email protected] /]#