Denis Excoffier <[EMAIL PROTECTED]> writes: >I'm not sure i understand all the implications of what Helmut has >written. I can add: >- of course the configure options would not be mandatory, and if not > set, the behaviour is like now
If the system administrator has configured tar to use a fixed location of the compressing programs rather than to search using the PATH environment variable, then there is nothing, a user could do against that, except: >- at individual level, to use a compress program of your own, you always > can take benefit of the --use-compress-program command line option thus the options '-z', '-Z', '-j' won't work anymore for that user. >- at site level, the selection of which versions of the > compress/gzip/bzip2/lzma programs to be used is done by the same > people as those that select (and configure, build, install) the > version of tar Yes, it's the administrator's choice. But the users should be given the chance to override it. >- with the --auto-compress option, you don't know in advance which > compress program will be used, therefore in my opinion you cannot use > --use-compress-program in this case I don't know the '--auto-compress' option (it's not listed yet in "http://www.gnu.org/software/tar/manual/html_node/tar_42.html#SEC42";), but probably it's the same problem as with '-z', '-Z' or '-j'. >- yes perhaps my proposal would also need the addition of a bypass > option, in order to the PATH to be used instead of the full path > selected at configure time Yes. But than I would rather like to see an option which tells tar to use the full path selected at configure time, thereby let tar by default do a PATH search: This would keep tar backward compatible with existing versions of tar. Someone, who'd like to use the new behavior, could put that option into the TAR_OPTIONS environment variable. >- i only wish to get the same mechanism as with the tar program > itself. You can say: > (PATH=/site/local/bin; tar etc.) > but you can also say > (/site/local/bin/tar etc.) > that is: not relying on the PATH if you don't want to > If you need to enforce a specific set of compress programs, you have to > wrap tar > into a subshell like the one Helmut proposes, this is too heavy in my > opinion, or... ... make sure, that the location of that specific set of compress programs is the first component of the PATH environment variable. > please Helmut show us your login shell!!! When you (interactively) log in to your account, then your shell will be invoked as a login shell by default (so it's quite normal to have a login shell). A login shell first reads commands from several startup files before it executes the given shell script or command line (supplied as a parameter to the option "-c") or prompts for commands to be executed. (For details of what a login shell does, see the manual page of the shell.) For example, a POSIX shell, when invoked as a login shell, first reads commands from the files "/etc/profile" and "$HOME"/.profile, if they exist, prior to do anything else. Thus a system administrator can (and really should) set the PATH environment variable by writing an appropriate command in the file "/etc/profile". Then users may change that variable in their "$HOME"/.profile files, if they want to, thereby being able to "configure" their own versions of "gzip", "compress", ... programs. A common pitfall is to use "su" without its option "-" when changing to a different user, because "su" invokes the new user's startup shell as a non-login shell unless given the option "-". As a non-login startup shell is almost never a good idea (not just because of the missing initialization of the PATH environment variable, but also for further parts of a process's environment, e.g. the umask), specifying the compress programs for tar at configure time wouldn't help much anyway. To make a long story short: If you want GNU tar to always use some special compress programs, you may put them in a directory of their own and then name the path of that directory as the first component of the PATH environment variable: If you want to do that as the system administrator, change the "export PATH=..." command in the file "/etc/profile", for example: export PATH=/site/local/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin If you want to do that as an ordinary user, you may put the command export \ PATH=/site/local/bin:"${PATH:-/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin}" into the file "$HOME"/.profile. Kind regards, Helmut -- Wer mir E-Mail schreiben will, stelle | When writing me e-mail, please bitte vor meine E-Mail-Adresse meinen | precede my e-mail address with Vor- und Nachnamen, etwa so: | my full name, like Helmut Waitzmann <[EMAIL PROTECTED]>, (Helmut Waitzmann) [EMAIL PROTECTED]
