a fast way to repeat output a byte

tr '\0' '\377' < /dev/zero|dd count=$((<bytes>/512))
the speed is about 500MB/s on my machine. i think it's fast enough to output not too many bytes. while a C program may output 1GB per sencond on my machine. if the size is not the power of 512,you may change the bs and count in dd.
Sample Output
$ time tr '\0' '\377' < /dev/zero|dd count=$((24*1024*2)) > /dev/null
49152+0 records in
49152+0 records out
25165824 bytes (25 MB) copied, 0.0491487 s, 512 MB/s
tr '\0' '\377' < /dev/zero  0.02s user 0.02s system 82% cpu 0.053 total
dd count=$((24*1024*2)) > /dev/null  0.01s user 0.03s system 76% cpu 0.052 total

4
By: cfy
2011-04-05 14:26:02

1 Alternatives + Submit Alt

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

You must be signed in to comment.

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

Share Your Commands



Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for: