In /usr/bin/debget line 29: echo "Usage: `basename $0` [--help] package" ^-----------^ SC2006: Use $(...) notation instead of legacy backticked `...`. ^-- SC2086: Double quote to prevent globbing and word splitting. Did you mean: echo "Usage: $(basename "$0") [--help] package" In /usr/bin/debget line 44: if ! ls /var/lib/apt/lists/ |grep Release >/dev/null; then ^-- SC2010: Don't use ls | grep. Use a glob or a for loop with a condition to allow non-alphanumeric filenames. In /usr/bin/debget line 50: for pkgspec in $*; do ^-- SC2048: Use "$@" (with quotes) to prevent whitespace problems. In /usr/bin/debget line 52: if [ $? -ne 0 ] ; then ^-- SC2181: Check exit code directly with e.g. 'if mycmd;', not indirectly with $?. For more information: https://www.shellcheck.net/wiki/SC2010 -- Don't use ls | grep. Use a glob o... https://www.shellcheck.net/wiki/SC2048 -- Use "$@" (with quotes) to prevent... https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...