All users share
/tmp (21.2),
so you should make unique filenames there.
The best way to do this is by putting $$
in the filename.
For example:
%vi /tmp/jerry.$$
"/tmp/jerry.12345" [New file] %lpr /tmp/jerry.$$
%rm /tmp/jerry.$$
The shell replaces $$
with the shell's
PID number (38.3)
(in this case, 12345
).
If you use a
subshell (38.4),
or have more than one login session or window,
and want to share the same temp file, $$
won't work for you.
In that case, just pick a unique name.
You could use today's date instead.
To give yourself both options with a minimum of work, here are lines for your shell setup files (2.2). The left column has lines for csh-like shells, and the right is for sh-like shells.
`...` [n] | .cshrc: .profile: set tf=/tmp/jp$$ tf=/tmp/jp$$ .login: export TF set date = (`date`) set `date` setenv TF /tmp/jp$date[4] TF=/tmp/jp$4 |
---|
(The last two lines grab the fourth word - the current time - from the output of the date (51.10) command.) When I want a temporary file in my current shell, I type:
* | % |
---|
The shell expands the
shell variable (6.8)
$tf-1
into a filename like /tmp/jp2345-1
, and
$tf-*
expands into all my temporary files in this shell.
Usually, that's great. But if I go to a subshell, do a shell escape,
and so on, the temporary files I make with $tf
won't be the
same as the ones I make in my login shell because the PIDs are
different. If I need them to be the same, I use $TF
, the
environment variable (6.1).
It's set to the time I logged in.
And because environment variables are passed to child shells, the name
(like /tmp/jp09:34:56) will be the same in subshells:
[..] | % |
---|
If I'll be using a file for more than a minute or two, I might forget
what's in which file.
So I leave myself a note in shell variables named xf
n
and environment variables named XF
n
-where "xf" means
"explain file" and n
is
1, 2, etc. to correspond to the variable.
If I don't remember which have what, I get a list by piping the output of
set (for shell variables) or
printenv or env (6.1)
(for environment variables) through grep.
For example:
%sort -t: +2 $tf-2 > $tf-3
%set xf3='sorted list of chapter 21 files'
...later... %set | grep xf
xf1 sorted list of chapter 20 files xf3 sorted list of chapter 21 files %lpr $tf-3
csh_logout sh_logout | To clean up when I log out, I added the lines that follow to the C shell .logout file. The Bourne shell version is similar, but it needs a couple of tricks to work on some shells; it's on the CD-ROM. |
---|
nonomatch -d |& $< =~ | # CLEAN FILES (IF ANY) OUT OF /tmp: set nonomatch set tmpf="\`ls -d $tf-* $TF-* |& grep -v ' not found'\`" if ( "$tmpf" =~ ?* ) then echo; echo "Your files in /tmp:" ls -d $tmpf echo -n "'rm -rf' them? [ny](n) " if ( "$<" =~ y* ) rm -rf $tmpf endif |
---|
If I made any temporary files from my login shell or any subshells, I get this message when I log out:
%logout
Your files in /tmp: /tmp/jp2345-1 /tmp/jp2345-2 /tmp/jp2748-1 /tmp/09:23:45-1 'rm -rf' them?y
Another way to do this is with a script like del (23.6).
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