convert a specific date to a unix timestamp

UNIX AIX
1

hello,

i have an AIX5.3 machine and i am writing a script to display some processes.
inside the script i want to get the time that the process starts and convert it to a unix timestamp.
is there a command that i can use to do that? i search the web but all i found is long scripts and it does not help me.
also note that i cannot use

date -d

command or

mktime

function.
note that i am not asking how to find a command to get the process or the time of the process. i can get the start time of the process the point is to be able to convert the time to a unix timestamp.

thank you in advance

2 
 
perl -e 'print localtime;'
3

this command doesnt seem to work for me.
i am using

echo <timestamp> | perl -e 'print localtime(<>) . "\n";'

to convert the timestamp into a human date.
but now i want to do the opposite, meaning converting a specific date into unix timestamp

4

Please post an example and explain in detail what you mean by a "unix timestamp".

The best time to record when a process starts is in the script you originally used to start the process.
Reading between the lines, it is quite difficult to work from the output from "ps".

5

by unix timestamp i mean the following:
when you run the command

date +%s

you have an output of an integer. this integer is the unix timestamp in my case. but also in my script i want to get this output by providing any given date. if i run

date +%s

i get the timestamp of the current date and time. i want to input a time to my script and the script display the timestamp of the time that i provided.