Create a 5 MB blank file via a seek hole

dd if=/dev/zero of=testfile.seek seek=5242879 bs=1 count=1
Similar to the original, but is much faster since it only needs to write the last byte as zero. A diff on testfile and testfile.seek will return that they are the same.

10
2011-04-04 17:56:47
dd

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What Others Think

By replacing /dev/zero with /dev/null it won't even write that single byte -- quicker still! Also, it makes the maths easier: you can abbreviate 5242880 to 5M (K = KiB, M = MiB, G = Gib, T = TiB) dd if=/dev/null of=testfile.seek seek=5M bs=1 count=0
flatcap · 376 weeks and 1 day ago
How about using truncate instead of dd. It is easier to use and faster than dd. truncate -s 5M testfile http://www.commandlinefu.com/commands/view/6850/create-a-file-of-a-given-size-in-linux
seungwon · 375 weeks and 6 days ago
The file has the good size but not consume space on disque. df -h /home Filesystem Size Used Avail Use% Mounted on /dev/mapper/rootvg-lv_home 1.9G 1.2G 607M 67% /home dd if=/dev/zero of=testfile.seek seek=1G bs=1 count=1 1+0 records in 1+0 records out 1 byte (1 B) copied, 0.000159075 s, 6.3 kB/s ll -h testfile.seek -rw-r--r-- 1 itsys grpit 1.1G Apr 7 16:27 testfile.seek df -h /home Filesystem Size Used Avail Use% Mounted on /dev/mapper/rootvg-lv_home 1.9G 1.2G 607M 67% /home
GouNiNi · 375 weeks and 5 days ago

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