> On 2018 Aug 6 , at 3:45 p, Chet Ramey <chet.ra...@case.edu> wrote: > > On 8/6/18 3:09 PM, Clint Hepner wrote: > >> Bash Version: 4.4 >> Patch Level: 19 >> Release Status: release >> >> Description: >> A non-initial unquoted tilde is expanded outside of an assignment. >> This >> was raised as a question on Stack Overflow, >> https://stackoverflow.com/q/51713759/1126841. >> >> Repeat-By: >> >> $ set +k >> $ echo home_dir=~ >> home_dir=/Users/chepner > > Yes. Bash has done this since its earliest days. A word that looks like an > assignment statement has tilde expansion performed after unquoted =~ and :~ > no matter where it appears on the command line. This makes things like > > make DESTDIR=~stager/bash-install > or > export PATH=/usr/local/bin:~/bin:/usr/bin > > easy and convenient.
Oh, right. For some reason, I had it in my head that this was only intended for builtins like export, and that their status as builtins somehow made the argument be treated as an assignment. I hadn't thought at all about non-builtin commands like make. > > The first version I can find that implemented the =~ and :~ tilde expansion > prefixes is bash-1.10 (1991). Those early versions would have expanded > something like `--home_dir=~'. The first version that restricted it to > words that satisfied the assignment statement restrictions is bash-2.0 > (1996). > > Bash doesn't do this when it's in posix mode. The first version that > implemented that was bash-1.14.0. > > -- > ``The lyf so short, the craft so long to lerne.'' - Chaucer > ``Ars longa, vita brevis'' - Hippocrates > Chet Ramey, UTech, CWRU c...@case.edu http://tiswww.cwru.edu/~chet/
