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In ksh88, the test/[ built-in supported both the '<' and '>'
lexical sorting comparison operators, same as in [[. However, in
every version of ksh93, '<' does not work though '>' still does!
Still, the code for both is present in test_binop():
src/cmd/ksh93/bltins/test.c
548: case TEST_SGT:
549: return(strcoll(left, right)>0);
550: case TEST_SLT:
551: return(strcoll(left, right)<0);
Analysis: The binary operators are looked up in shtab_testops[] in
data/testops.c using a macro called sh_lookup, which expands to a
sh_locate() call. If we examine that function in sh/string.c, it's
easy to see that on systems using ASCII (i.e. all except IBM
mainframes), it assumes the table is sorted in ASCII order.
src/cmd/ksh93/sh/string.c
64: while((c= *tp->sh_name) && (CC_NATIVE!=CC_ASCII || c <= first))
The problem was that the '<' operator was not correctly sorted in
shtab_testops[]; it was sorted immediately before '>', but after
'='. The ASCII order is: < (60), = (61), > (62). This caused '<' to
never be found in the table.
The test_binop() function is also used by [[, yet '<' always worked
in that. This is because the parser has code that directly checks
for '<' and '>' within [[ (in sh/parse.c, lines 1949-1952).
This commit also adds '=~' to 'test', which took three lines of
code and allowed eliminating error handling in test_binop() as
test/[ and [[ now support the same binary ops. (re:
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|---|---|---|
| .. | ||
| args.c | ||
| arith.c | ||
| array.c | ||
| defs.c | ||
| deparse.c | ||
| expand.c | ||
| fault.c | ||
| fcin.c | ||
| init.c | ||
| io.c | ||
| jobs.c | ||
| lex.c | ||
| macro.c | ||
| main.c | ||
| name.c | ||
| nvdisc.c | ||
| nvtree.c | ||
| nvtype.c | ||
| parse.c | ||
| path.c | ||
| pmain.c | ||
| shcomp.c | ||
| streval.c | ||
| string.c | ||
| subshell.c | ||
| suid_exec.c | ||
| tdump.c | ||
| timers.c | ||
| trestore.c | ||
| waitevent.c | ||
| xec.c | ||