Make the 'history' and 'r' commands builtins

[JohnoKing]

This pull request makes history and r commands builtins that aren't limited to interactive shells. All ksh commands can now be used without unalias -a removing them (unalias -a in .kshrc no longer removes history and r). With this change no more preset aliases exist, so the preset alias tables can be safely removed. The alias tree is now initialized in the same way as the function tree:

ksh/src/cmd/ksh93/sh/init.c

Line 1858 in 17f81eb

shp->fun_tree = dtopen(&_Nvdisc,Dtoset);

The sh_inittree code for comparison:

ksh/src/cmd/ksh93/sh/init.c

Line 1900 in 17f81eb

base_treep = treep = dtopen(&_Nvdisc,Dtoset);

[McDutchie]

Are there actually scripts that use these?

[JohnoKing]

Are there actually scripts that use these?

I'm not sure about r, but regarding history there is at least one person that was using the (Bash) history command in a script: https://askubuntu.com/questions/546556/how-can-i-use-history-command-in-a-bash-script
In any case this change was made so unalias -a in the kshrc file doesn't remove the r and history commands from interactive shells, since that wasn't addressed in commit 17f81eb.

[McDutchie]

True. My assumption was that no existing .kshrc is going to run unalias -a if it wants to keep those aliases. Since these were the only two default aliases that actually made sense as such, I figured my approach fixed things with the minimum change necessary.

OTOH, your approach makes everything consistent and simplifies the code, and that is good. And your way of initialising an empty alias table is clearly better.

I have a couple of tweaks (particularly sh_opthist[] documentation; e.g. now r --man output is weird) but it's probably easiest if I just push those myself.

[hyenias]

@JohnoKing @McDutchie:
Help me clarify as to what will happen when my .kshrc issues unalias 2d fc r. I believe you have already removed the 2d functionality. In particular, a have issues with any 1-2 character commands (I do not like stuff happening when a keyboard mishap occurs). As history commands are not something I run that often, simply typing out history or the related hist builtin is easy. However, the fc and r commands fall into my category of must remove. Perhaps instead of issuing unalias I will be able to use builtin -d <name>. Correct?

[JohnoKing]

builtin -d will work on all of the commands that were previously aliases except times (since that one is a special builtin). fc and r can be removed with builtin -d fc r.

[hyenias]

Excellent. Thank you!