You didn't really define "old" so I guess responses are going to be varied. Here is mine:
- Python (mentioning since it is over 20/25 years old, though used a lot currently by many, of course).
- C (evergreen, for some uses, IMO)
- sh / bash, with sed/awk and friends (the common Unix command-line power tools (filters and others))
(Talking about both of the two points above mainly on Unix / Linux, though both are quite useful on Windows too - sh / bash and friends via cygwin, UWin, Ch and similar tools, and now / after some time with the Windows Subsystem For Linux.)
- D (if it can be called an old one)
- Probably Pascal (via FreePascal), for small tools, for fun and personal dev use (e.g. utilities), on the side, to start with, maybe see if I can make something bigger and generally useful later (I have a somewhat long prior background in it - and in C). The compile times are fast, like D and Go, and executables are small, which are two of the reasons. Haven't checked runtime performance of it much yet, but likely will not be shabby, to say the least. And last but not least (reason), because it is like C with some niceties added, which makes the code more human-readable and maintable (though I have no trouble understanding well-written C, my own or others'.) Also, modern Pascals like Delphi's Object Pascal and Free Pascal are a far cry (much better) than the academic Pascal versions that were taught in universities years ago.
Edited to add (after seeing others mention it):
- SQL (had forgotten it because it is a bread-and-butter thing used in most of my projects, irrespective of other language used)
- Python (mentioning since it is over 20/25 years old, though used a lot currently by many, of course).
- C (evergreen, for some uses, IMO)
- sh / bash, with sed/awk and friends (the common Unix command-line power tools (filters and others))
(Talking about both of the two points above mainly on Unix / Linux, though both are quite useful on Windows too - sh / bash and friends via cygwin, UWin, Ch and similar tools, and now / after some time with the Windows Subsystem For Linux.)
- D (if it can be called an old one)
- Probably Pascal (via FreePascal), for small tools, for fun and personal dev use (e.g. utilities), on the side, to start with, maybe see if I can make something bigger and generally useful later (I have a somewhat long prior background in it - and in C). The compile times are fast, like D and Go, and executables are small, which are two of the reasons. Haven't checked runtime performance of it much yet, but likely will not be shabby, to say the least. And last but not least (reason), because it is like C with some niceties added, which makes the code more human-readable and maintable (though I have no trouble understanding well-written C, my own or others'.) Also, modern Pascals like Delphi's Object Pascal and Free Pascal are a far cry (much better) than the academic Pascal versions that were taught in universities years ago.
Edited to add (after seeing others mention it):
- SQL (had forgotten it because it is a bread-and-butter thing used in most of my projects, irrespective of other language used)