On Sat, 6 Apr 2019, Dmitry Bogatov wrote: > [2019-04-05 11:11] Cristian Ionescu-Idbohrn > <[email protected]> > > Thing is neither the `:' nor the `true' commands are needed. To > > truncate a file it's sufficient to redirect _nothing_ to that file. > > > > $ dash -c '>/tmp/dir/; echo $?; echo hello world;' > > dash: 1: cannot create /tmp/dir/: Is a directory > > 2 > > hello world > > Nice to know. Is this behaviour mandated by posix?
Not in so many words, but it doesn't say there _must_ be input to redirect to stdout or stderr. http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_07 "The overall format used for redirection is: [n]redir-op word" (nothing about input). dash, bash, busybox ash work fine, but not zsh (it's waiting for input). I've been using these redirections for many, many years without any ill effects: >file # truncate or create >>file # `touch' or create > > The real problem is that a failing redirection is _not_ error handled > > (in the /etc/init.d/bootmisc.sh case). > > Sorry, failed to parse. You seems to tell, that there is another problem > in 'bootmisc.sh', but I do not understand, which one. The redirection in /etc/init.d/bootmisc.sh on line 29 is _not_ error handled. Writing to a file can fail (for various reasons). OTOH, the redirection in /lib/init/bootclean.sh on line 22 _is_ error handled. Cheers, -- Cristian
