me@mybox:/home/me/sandbox
$ cat 1.pl
#!/usr/bin/perl
system('echo bob >/tmp/blarney.out');
me@mybox:/home/me/sandbox
$ ./1.pl
me@mybox:/home/me/sandbox
$ cat /tmp/blarney.out
bob
me@mybox:/home/me/sandbox
$ rm /tmp/blarney.out
me@mybox:/home/me/sandbox
$ at -f 1.pl now
Job me.1323356661.a will be run at Thu Dec  8 10:04:21 EST 2011.
me@mybox:/home/me/sandbox
$ at -l
me@mybox:/home/me/sandbox
$ ls -l /tmp/blarney.out
ls: 0653-341 The file /tmp/blarney.out does not exist.

##</code><code>##

me@mybox:/home/me/sandbox
$ mail
Mail [5.2 UCB] [AIX 5.X]  Type ? for help.
"/var/spool/mail/me": 2 messages 1 new 2 unread
 U  1 daemon            Thu Dec  8 10:02  32/950  "Output from at job 1.pl, me"
>N  2 daemon            Thu Dec  8 10:04  31/940  "Output from at job 1.pl, me"
? 1
Message  1:
From daemon Thu Dec  8 10:02:08 2011
Date: Thu, 8 Dec 2011 10:02:08 -0500
From: daemon
To: me
Subject: Output from at job 1.pl, me@mybox, exit status 127

Cron Environment:
 SHELL = /opt/freeware/bin/bash
 PATH=/usr/bin:/etc:/usr/sbin:/usr/bin/X11:/sbin:/usr/java14/jre/bin:/usr/java14/bin:/usr/local/bin
 CRONDIR=/var/spool/cron/crontabs
 ATDIR=/var/spool/cron/atjobs
 LOGNAME=me
 HOME=/home/me

Your "at" job executed on mybox on Thu Dec  8 10:02:08 EST 2011
1.pl


produced the following output:

bash: line 3: 1.pl: command not found


*****************************************************************
        cron: The previous message is the standard output
        and standard error of one of the cron commands.

##</code><code>##

me@mybox:/home/me/sandbox
$ ls -l /tmp/blarney.out
ls: 0653-341 The file /tmp/blarney.out does not exist.
me@mybox:/home/me/sandbox
$ at -f /home/me/sandbox/1.pl now
Job me.1323356887.a will be run at Thu Dec  8 10:08:07 EST 2011.
me@mybox:/home/me/sandbox
$ at -l
me@mybox:/home/me/sandbox
$ ls -l /tmp/blarney.out
-rw-r-----    1 me users             4 Dec 08 10:08 /tmp/blarney.out