Op 04-10-17 om 17:52 schreef Chet Ramey:
> It's interesting that other shells treat ${a:=b} as kind of like an
> assignment statement (word splitting) but not quite (tilde expansion).
Hmm...
v=~/bla
printf '%s\n' "$v"
outputs /Users/martijn/bla on all shells, so tilde expansion applies for
a simple assignment anyway.
And
unset -v v
v=${v:=~/bla}
printf '%s\n' "$v"
acts exactly the same.
This is all POSIXly correct, IIRC.
Of course, when ${v:=~/bla} is an unquoted expansion in a non-assignment
context, field splitting and pathname expansion apply to the expansion,
but not to the assignment itself, which is also perfectly logical:
[ -n "${ZSH_VERSION+s}" ] && emulate sh
unset -v v
touch /tmp/foo.bar /tmp/baz.bar
printf 'field: [%s]\n' ${v:=~/one ~/two /tmp/*.bar}
printf ' var: [%s]\n' "$v"
Output on bash, dash, FreeBSD sh, Busybox ash, yash, pdksh, mksh, ksh93,
zsh up to 5.0.8:
field: [/Users/martijn/one]
field: [~/two]
field: [/tmp/baz.bar]
field: [/tmp/foo.bar]
var: [/Users/martijn/one ~/two /tmp/*.bar]
Output on zsh 5.1 and later, it seems to do tilde expansion after word
splitting instead of before -- which looks like a bug[*2], I'll take
that up there:
field: [/Users/martijn/one]
field: [/Users/martijn/two]
field: [/tmp/baz.bar]
field: [/tmp/foo.bar]
var: [/Users/martijn/one ~/two /tmp/*.bar]
Output on bosh (schilytools) and NetBSD sh -- clearly a bug, it doesn't
do tilde expansion at all:
field: [~/one]
field: [~/two]
field: [/tmp/baz.bar]
field: [/tmp/foo.bar]
var: [~/one ~/two /tmp/*.bar]
- Martijn
[*1]
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_01
[*2]
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06
