Pressing the TAB-key (denoted by <press TAB> below on an empty input line produces the following error message: # <press TAB>bash: words: bad array subscript <CURSOR> and the cursor ends up in the next line (denoted by <CURSOR> above). Trying to get to the ground of the issue by using set -x in the active bash shell it turns out that file .pre under /usr/share/bash-completion seems to be the culprit. The relevant lines are starting from 669 and read as follows: [[ $cword -eq 0 ]] && return 1 prev=${words[cword-1]} During the execution with an empty line the variable word contains -1 which results in words[-2] to be evaluated - and that seems to be a bad array subscript. Changing the line [[ $cword -eq 0 ]] && return 1 to instead read [[ $cword -le 0 ]] && return 1 fixes the error message and rings the terminal bell to (rightly) denote no completion possible. All other (valid) completions seem unaffected by this change. Reproducible: Always Steps to Reproduce: 1. press the <TAB>-key on an empty input line in bash with bash-completion active Actual Results: Error message "bash: words: bad array subscript" Expected Results: Terminal bell to indicate that no completion could be performed Portage 2.2.18 (python 2.7.9-final-0, hardened/linux/amd64, gcc-4.8.4, glibc-2.20-r2, 3.18.9-hardened x86_64) ================================================================= System uname: Linux-3.18.9-hardened-x86_64-Intel-R-_Xeon-R-_CPU_E31260L_@_2.40GHz-with-gentoo-2.2 KiB Mem: 4033128 total, 227164 free KiB Swap: 16777148 total, 16777148 free Timestamp of repository gentoo: Sat, 30 May 2015 23:45:01 +0000 sh bash 4.3_p33-r2 ld GNU ld (Gentoo 2.24 p1.4) 2.24 app-shells/bash: 4.3_p33-r2::gentoo dev-lang/perl: 5.20.2::gentoo dev-lang/python: 2.7.9-r1::gentoo, 3.4.1::gentoo dev-util/cmake: 2.8.12.2-r1::gentoo dev-util/pkgconfig: 0.28-r2::gentoo sys-apps/baselayout: 2.2::gentoo sys-apps/openrc: 0.13.11::gentoo sys-apps/sandbox: 2.6-r1::gentoo sys-devel/autoconf: 2.69::gentoo sys-devel/automake: 1.13.4::gentoo, 1.14.1::gentoo sys-devel/binutils: 2.24-r3::gentoo sys-devel/gcc: 4.8.4::gentoo sys-devel/gcc-config: 1.7.3::gentoo sys-devel/libtool: 2.4.6::gentoo sys-devel/make: 4.1-r1::gentoo sys-kernel/linux-headers: 3.18::gentoo (virtual/os-headers) sys-libs/glibc: 2.20-r2::gentoo Repositories: gentoo location: /usr/portage sync-type: rsync sync-uri: rsync://rsync.europe.gentoo.org/gentoo-portage/ priority: -1000 x-portage location: /usr/local/portage masters: gentoo priority: 0 ACCEPT_KEYWORDS="amd64" ACCEPT_LICENSE="* -@EULA" CBUILD="x86_64-pc-linux-gnu" CFLAGS="-march=native -O2 -pipe -fomit-frame-pointer" CHOST="x86_64-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/share/gnupg/qualified.txt" CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/env.d /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo" CXXFLAGS="-march=native -O2 -pipe -fomit-frame-pointer" DISTDIR="/usr/portage/distfiles" EMERGE_DEFAULT_OPTS="--quiet-build=y --buildpkg-exclude sys-kernel/hardened-sources" FCFLAGS="-O2 -pipe" FEATURES="assume-digests binpkg-logs buildpkg config-protect-if-modified distlocks ebuild-locks fixlafiles merge-sync news parallel-fetch preserve-libs protect-owned sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv usersandbox usersync xattr" FFLAGS="-O2 -pipe" GENTOO_MIRRORS="http://gd.tuwien.ac.at/opsys/linux/gentoo/ ftp://gd.tuwien.ac.at/opsys/linux/gentoo/" LANG="en_US.UTF-8" LDFLAGS="-Wl,-O1 -Wl,--as-needed" MAKEOPTS="-j9" PKGDIR="/usr/portage/packages" PORTAGE_COMPRESS="" PORTAGE_CONFIGROOT="/" PORTAGE_RSYNC_EXTRA_OPTS="--quiet --progress" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --omit-dir-times --compress --force --whole-file --delete --stats --human-readable --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages" PORTAGE_TMPDIR="/var/tmp" USE="acl aes amd64 avx bash-completion berkdb bzip2 cli cracklib crypt cxx gdbm hardened iconv justify lm_sensors mmx mmxext modules multilib ncurses nls nptl openmp pam pax_kernel pcre popcnt readline session sse sse2 sse3 sse4.1 sse4_1 ssl ssse3 tcpd unicode urandom vim-syntax xattr xtpax zlib" ABI_X86="64" CPU_FLAGS_X86="aes avx mmx mmxext popcnt sse sse2 sse3 sse4_1 sse4.1 ssse3" ELIBC="glibc" KERNEL="linux" LINGUAS="en" PHP_TARGETS="php5-5" PYTHON_SINGLE_TARGET="python2_7" PYTHON_TARGETS="python2_7" RUBY_TARGETS="ruby20" USERLAND="GNU" VIDEO_CARDS="intel i965" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq steal rawnat logmark ipmark dhcpmac delude chaos account" USE_PYTHON="2.7" Unset: CPPFLAGS, CTARGET, INSTALL_MASK, LC_ALL, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS_FLAGS
I'd argue it shouldn't return in such case, but act as bash originally did: return full list of completions. So, IMHO, this: if [[ $cword -ne -1 ]]; then prev=${words[cword-1]} fi gives a better result. Probably could be made more compact, but I don't now shell all that well.
...though that's not quite right either: it should return the list from $PATH in such case, not its own list,,,
I think this has been fixed upstream a while ago. I can't reproduce it with the newest version.
