Control: tags -1 + confirmed upstream Hello James Cowgill,
Thanks for your bug report. On Wed, Jan 25, 2017 at 02:57:01PM +0000, James Cowgill wrote: [...] > As the subject says, if there is no pager installed then the fdisk 'l' > command does not work. Example: [...] > > Command (m for help): l > > sh: 1: less: not found > > Yes, less is used if PAGER is unset: http://sources.debian.net/src/util-linux/2.29.1-1/lib/pager.c/#L181 This problem can also be reproduced by using: PAGER="foobar" fdisk /dev/sda We could carry a patch in Debian to make 'sensible-pager' the default (instead of less) but even that can sometimes fail, so I'd rather see the case of not being able to start the pager handled. The start_command function tries to promise us that it'll close the pager fd if launching the pager fails: http://sources.debian.net/src/util-linux/2.29.1-1/lib/pager.c/#L59 Unfortunately its attempt is not good enough, since the pager is wrapped in 'sh -c $PAGER' (to search PATH for the given pager?): http://sources.debian.net/src/util-linux/2.29.1-1/lib/pager.c/#L25 http://sources.debian.net/src/util-linux/2.29.1-1/lib/pager.c/#L187 This means we'll always succeed in exec:ing the process, but then sh will exit with an error code later when it doesn't find the actual pager program. When sh exits, it's already to late for start_command to catch that. Help welcome in figuring out a way to catch this case. Possibly hooking up SIGCHLD and introducing a small delay in the end of pager_open could work, but the delay has to be small enough to not be annoying (less than half a second?) and large enough for slow machines to have time (likely several seconds?). I guess there's no way to please everybody so maybe just waiting a short time is good enough for most cases even though not completely reliable. Another option might be to make the util-linux build system detect full path of less during configure, then add code to check if the file exists or bail out early at: http://sources.debian.net/src/util-linux/2.29.1-1/lib/pager.c/#L59 The latter one might be the better solution as it should be more reliable. It doesn't solve the PAGER="foobar" case but I guess you get to keep both halves if you actively break it like that. > > Setting PAGER=/bin/more (which obviously will exist) can workaround it, > but fdisk should fallback to that automatically when less does not exist > (or just use that anyway when PAGER is not set). Another workaround is to disable paging which can be done using: PAGER="" fdisk /dev/sda (Using PAGER="cat" also works.) Regards, Andreas Henriksson
