Re: The "which -s" flag
On Fri, 14 Aug 2020 at 00:55:03 +0200, Erik Gustafsson wrote:
> This "which" is heavily used at the company where I work, for java
> development etc like
> which -s java || echo "You have to install java to run this program"
Another angle you could attack this from is to change these scripts to
use "which java >/dev/null" or, better, "command -v java >/dev/null"
instead of "which -s java".
which(1) is non-standardized, which is likely to be part of the reason
why Debian has its own implementation not shared with other Linux
distributions. Some other Linux distributions, for example Fedora and
Arch Linux, use GNU Which <https://savannah.gnu.org/projects/which/> and
that doesn't seem to support the -s option either (but does support a lot
of other non-standard options). Adding a -s option to the debianutils
implementation of `which` will help your scripts to run on Debian and
(eventually) Debian derivatives like Ubuntu, but won't help your scripts
to run on Fedora or Arch. Other distributions might be using debianutils
`which` like Debian, GNU Which like Fedora, or some third implementation.
command(1) is specified by POSIX
(https://pubs.opengroup.org/onlinepubs/9699919799/utilities/command.html)
and should be available on all Unix-like systems, with at least the
options documented in POSIX.
(This is not a reason to reject the addition of a -s option to which -
if users of other systems expect that option, it might as well exist -
but it might well be a quicker route to portability than patching all
the implementations of which.)
smcv
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