Removing created temp files in unexpected bash exit

Question

I am creating temporary files from a bash script. I am deleting them at the end of the processing, but since the script is running for quite a long time, if I kill it or simply

Answer 1

You could set a "trap" to execute on exit or on a control-c to clean up.

trap '{ rm -f -- "$LOCKFILE"; }' EXIT

Alternatively, one of my favourite unix-isms is to open a file, and then delete it while you still have it open. The file stays on the file system and you can read and write it, but as soon as your program exits, the file goes away. Not sure how you'd do that in bash, though.

BTW: One argument I'll give in favour of mktemp instead of using your own solution: if the user anticipates your program is going to create huge temporary files, he might want set TMPDIR to somewhere bigger, like /var/tmp. mktemp recognizes that, your hand-rolled solution (second option) doesn't. I frequently use TMPDIR=/var/tmp gvim -d foo bar, for instance.

Answer 2

You don't have to bother removing those tmp files created with mktemp. They will be deleted anyway later.

Use mktemp if you can as it generates more unique files then '$$' prefix. And it looks like more cross platform way to create temp files then explicitly put them into /tmp.

Answer 3

You want to use the trap command to handle exiting the script or signals like CTRL-C. See the Greg's Wiki for details.

For your tempfiles, using basename $0 is a good idea, as well as providing a template that provides room for enough temp files:

tempfile() {
    tempprefix=$(basename "$0")
    mktemp /tmp/${tempprefix}.XXXXXX
}

TMP1=$(tempfile)
TMP2=$(tempfile)

trap 'rm -f $TMP1 $TMP2' EXIT

Answer 4

I prefer using tempfile which creates a file in /tmp in the safe manner and you do not have to worry about its naming:

tmp=$(tempfile -s "your_sufix")
trap "rm -f '$tmp'" exit

Answer 5

I cannot believe that so many people assume that a file name will not contain a space. The world will crash if $TMPDIR is ever assigned to "temporary directory".

zTemp=$(mktemp --tmpdir "$(basename "$0")-XXX.ps")
trap "rm -f ${zTemp@Q}" EXIT

Spaces and other special characters like single quotes and carriage returns in file names should be considered in code as a requirement of decent programming habit.

Answer 6

I usually create a directory in which to place all my temporary files, and then immediately after, create an EXIT handler to clean up this directory when the script exits.

MYTMPDIR="$(mktemp -d)"
trap 'rm -rf -- "$MYTMPDIR"' EXIT

If you put all your temporary files under $MYTMPDIR, then they will all be deleted when your script exits in most circumstances. Killing a process with SIGKILL (kill -9) kills the process right away though, so your EXIT handler won't run in that case.