Features Introduced Past 1979
Over the years, the Bourne shell was enhanced at AT&T. The various variants are thus called like the respective AT&T Unix version it was released with (some important variants being Version7, SystemIII, SVR2, SVR3, SVR4). As the shell was never versioned, the only way to identify it was testing its features.
Features of the Bourne shell versions since 1979 include:
- Built-in test command – System III shell (1981)
- # as comment character – System III shell (1981)
- Colon in parameter substitutions "${parameter:=word}" – System III shell (1981)
- Functions and the return builtin – SVR2 shell (1984)
- Built-ins unset, echo, type – SVR2 shell (1984)
- Source code de-ALGOL68-ized – SVR2 shell (1984)
- Modern "$@" – SVR3 shell (1986)
- Built-in getopts – SVR3 shell (1986)
- Cleaned up parameter handling allows recursively callable functions – SVR3 shell (1986)
- 8-bit clean – SVR3 shell (1986)
- Job control – SVR4 shell (1989)
- Multi-byte support – SVR4 shell (1989)
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