Robert Elz wrote in <6906.1680741...@jacaranda.noi.kre.to>: ... |The issue here is that people tend to think of | a=1 |as a command. It isn't (not as people think of it anyway). |But with that mindset they treat | a=1 b=$a c=$b |as 3 commands, one after the other. It isn't.
To come back to the bug i reported to FreeBSD ([1]). [1] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=251770 There i say 3385 4.23 Variable Assignment 3386 In the shell command language, a word consisting of the following parts: 3387 varname=value 3388 When used in a context where assignment is defined to occur and at no other time, the value 3389 (representing a word or field) shall be assigned as the value of the variable denoted by varname. 3390 Note: For further information, see XCU Section 2.9.1 (on page 2365). --- 75482 2.9.1 Simple Command 75495 4. Each variable assignment shall be expanded for tilde expansion, parameter expansion, 75496 command substitution, arithmetic expansion, and quote removal prior to assigning the 75497 value. --- 75501 Variable assignments shall be performed as follows: 75502 • If no command name results, variable assignments shall affect the current execution 75503 environment. --- So everything should be handled sequentially, making it a bug. And that is true, no? If expansion has to take place, and the assignment has been performed, .. it has been performed? --- 75504 • If the command name is not a special built-in utility or function, the variable assignments [.] 75507 4. In this case it is unspecified: 75508 — Whether or not the assignments are visible for subsequent expansions in step 4 75509 — Whether variable assignments made as side-effects of these expansions are visible for 75510 subsequent expansions in step 4, or in the current shell execution environment, or 75511 both --- So it allows to setup the "execution environment of the command" entirely from the current environment, which is effectively read-only. As you say. So maybe null command and that is not a bug? But all shells except FreeBSD do this; also from the report: #?2|kent$ for s in dash bash mksh bosh; do $s -c 'du=ich wir='"'"'hey '"'"'$du; echo $wir'; done hey ich hey ich hey ich hey ich I am no shell expert whatsoever. My mailer will never support that (except for assignment in arithmetic expression eg $((i=1))): This behaviour is different to the SHELL[644], which is a programming language with syntactic elements of clearly defined semantics, and there‐ fore capable to sequentially expand and evaluate individual elements of a line. ‘? set one=spoon two=$one’ for example will never assign ‘spoon’ to two, because it is the command set[275] that performs the assignment, long after the expansion has happened. So i am out. --steffen | |Der Kragenbaer, The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt)
