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author | Tom Ryder <tom@sanctum.geek.nz> | 2017-04-05 20:06:39 +1200 |
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committer | Tom Ryder <tom@sanctum.geek.nz> | 2017-04-05 20:46:47 +1200 |
commit | c8ab406749124d2e762ad5cf53963070113afd0f (patch) | |
tree | 54c9721a06957ebe7098a211eea803b0230c0f5d /bin/rnds.sh | |
parent | Handle POSIX correctness in ~/.bash_profile (diff) | |
download | dotfiles-c8ab406749124d2e762ad5cf53963070113afd0f.tar.gz dotfiles-c8ab406749124d2e762ad5cf53963070113afd0f.zip |
Apply runtime shebanging to POSIX shell
Diffstat (limited to 'bin/rnds.sh')
-rw-r--r-- | bin/rnds.sh | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/bin/rnds.sh b/bin/rnds.sh new file mode 100644 index 00000000..6b3ac904 --- /dev/null +++ b/bin/rnds.sh @@ -0,0 +1,21 @@ +# Try to get a low-quality random seed from a random device if possible + +# Sole optional argument is the bytes to read; 32 is the default +count=${1:-32} + +# Try and find a random device to use; none of these are specified by POSIX +for dev in /dev/urandom /dev/arandom /dev/random '' ; do + [ -e "$dev" ] && break +done + +# Bail if we couldn't find a random device +[ -n "$dev" ] || exit 1 + +# Read the bytes from the device +dd if="$dev" bs=1 count="$count" 2>/dev/null | + +# Run cksum(1) over the read random bytes +cksum | + +# cut(1) the cksum(1) output to only the first field, and print that to stdout +cut -d' ' -f1 |