what is so special about /tmp/




i know that /tmp is used for memory or swap??? and that it should not be full ??? and that files under /tmp are automatically removed after a reboot???


is this info true???

it depends on the os. some clear it out and others do not. others have /tmp the same as swap and others don't. which os are you asking about?

thx.
why is it a common practice to create hidden files and directories under /tmp??

unless we are going to prohibit the use of temporary files, we needed some place that programs can use for temporary files. you can't just create a file anywhere, there may not be enough space and/or the directory permissions may prohibit it. to create a file in say, /a/b/c/something, you must have read and search permission on /a, /a/b, and /a/b/c. some time is required to check all of that, so for overall speed, a place of the form simply /something (that is, some top level directory) is better. now we need a name for "something" and the ancient ones went with /tmp. memory was very tight in the 60's and 70's and this argued for short names. /tmp is as short as you can get while still being somewhat obvious in intent.