For values of Unix approximating Linux or BSD, your programs come with sources, and/or have been incrementally updated along with the OS. There are very few specific applications from 15 years ago that I have any interest in running, though there are capabilities I had and/or syntaxes I might want to use/rely on.
I started using UNIX in 1987. Among the tools I used at the time were sh/csh, vi, cc, telnet, talk, sed, awk, find, and grep. All are either still present in their original or evolved forms (grep, sed, gawk, GNU find, gcc, vim, talk/irssi), or have been replaced by more appropriate and/or secure tools (bash, ssh for telnet), I prepared more than one paper using nroff macros (groff today).
While these are for the most part text/console tools, the point is that over nearly a quarter century I've been able to build on rather than periodically toss out wholesale, a set of technical skills. Underlying concepts such as TCP/IP, filesystem hierarchies, daemon startup, process monitoring, etc., have similarly remained fairly constant.
In the personal computing world I watched CPM, Amiga, BeOS, nine or ten iterations of Windows/DOS (each with many gratuitous changes), and several major iterations of the Mac platform come and go, among others.
While the proprietary Unix market did fragment, and has ultimately fallen under the licensing correction of Free Software (thank you, RMS), that was ultimately a false start.
Microsoft managed to create platform uniformity through compulsory licensing arrangements with bulk OEMs (Compaq, IBM, Dell, HP, and others), quashing the competition (particular QDOS/DRDOS and others). The binary backwards compatibility is somewhat impressive, but comes at a high cost, and one which today with emulation readily available is rather much a throwback.
I started using UNIX in 1987. Among the tools I used at the time were sh/csh, vi, cc, telnet, talk, sed, awk, find, and grep. All are either still present in their original or evolved forms (grep, sed, gawk, GNU find, gcc, vim, talk/irssi), or have been replaced by more appropriate and/or secure tools (bash, ssh for telnet), I prepared more than one paper using nroff macros (groff today).
While these are for the most part text/console tools, the point is that over nearly a quarter century I've been able to build on rather than periodically toss out wholesale, a set of technical skills. Underlying concepts such as TCP/IP, filesystem hierarchies, daemon startup, process monitoring, etc., have similarly remained fairly constant.
In the personal computing world I watched CPM, Amiga, BeOS, nine or ten iterations of Windows/DOS (each with many gratuitous changes), and several major iterations of the Mac platform come and go, among others.
While the proprietary Unix market did fragment, and has ultimately fallen under the licensing correction of Free Software (thank you, RMS), that was ultimately a false start.
Microsoft managed to create platform uniformity through compulsory licensing arrangements with bulk OEMs (Compaq, IBM, Dell, HP, and others), quashing the competition (particular QDOS/DRDOS and others). The binary backwards compatibility is somewhat impressive, but comes at a high cost, and one which today with emulation readily available is rather much a throwback.