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dd
if=/dev/zero of=dummyfile bs=26214400 count=1
1+0
records in
1+0
records out
26214400
bytes (26 MB) copied, 0.063799 seconds, 411 MB/s
$
ls -ltr
total
25632
-rw-r--r--
1 oracle oinstall 26214400 Nov 3 11:42
dummyfile
Read
from /dev/zero
file will return the null characters as requested in the read operation.
/dev/zero is a file similar to /dev/null
dd if=/dev/zero of=dummyfile bs=26214400 count=1
where
if
: input file
of : output file
bs :bytes – By default value considered as
bytes. Also you can specify in MB(M) or GB(G)
count : number of input blocks is of size mentioned
in bs parameter.
More
command will display some blank lines.
$
more dummyfile
$
dd if=/dev/zero of=dummyfile bs=1024 count=1
1+0
records in
1+0
records out
1024
bytes (1.0 kB) copied, 7.3e-05 seconds, 14.0 MB/s
$
dd if=/dev/zero of=dummyfile1 bs=1024 count=1024
1024+0
records in
1024+0
records out
1048576
bytes (1.0 MB) copied, 0.007779 seconds, 135 MB/s
$
ls -ltr
total
1032
-rw-r--r--
1 oracle oinstall 1024 Nov 3 11:54 dummyfile
-rw-r--r--
1 oracle oinstall 1048576 Nov 3 11:54
dummyfile1
Suppose
if you wanted to create a 50 MB file you can use bs as 1M and count as 50. Which
means filesize is bs x count
$
dd if=/dev/zero of=dummyfile1 bs=1M count=50
50+0
records in
50+0
records out
52428800
bytes (52 MB) copied, 0.14089 seconds, 372 MB/s
$
ls -ltr
total
51256
-rw-r--r--
1 oracle oinstall 52428800 Nov 3 11:57
dummyfile1
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