Package: dash
Version: 0.5.7-4+b1
Severity: normal
In Bourne shell script with dash, using either [ ] or test,
test -n "${variable}" && echo "variable is set to -->${variable}<--"
works as expected even if the value of variable is to a value the same
as a test operator eg -ne or -nt
variable="-ne" ; test -n "${variable}" && echo "variable is set to
-->${variable}<--"
variable is set to -->-ne<--
However the addition of another test condition with -a or -o results in an
unexpected behavior in that the expanded variable is now treated as an operator
and not just as the string as should be the case.
variable="-ne" ; test -n "${variable}" -a -n "${DISPLAY}" && echo "variable
is set to -->${variable}<--"
dash: 1: test: Illegal number: -n
Applying quoted parentheses makes no difference.
variable="-ne" ; test \( -n "${variable}" \) -a \( -n "${DISPLAY}" \) &&
echo "variable is set to -->${variable}<--"
dash: 2: test: Illegal number: -n
Similarly bad behavior is seen with a variable set to "-nt", which is how I
stumbled upon this problem.
variable="-nt" ; test \( -n "${variable}" \) -a \( -n "${DISPLAY}" \) &&
echo "variable is set to -->${variable}<--"
dash: 3: test: closing paren expected
So if the test is consists of a single condtion, the expanded variable does not
cause
problems with the test, and should not affect the test if it is part of a
multiple condition test.
Incidentally bash also has this problem.
So the short term kludge in a shell script is to do
if [ -n "${variable_with_problem_value}" ]
then
if [ \( other_condition1 \) -a \( other_condition2 \) ]
then
...
-- System Information:
Debian Release: 8.6
APT prefers stable-updates
APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: armel (armv5tel)
Kernel: Linux 3.16.0-4-kirkwood
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=ANSI_X3.4-1968)
(ignored: LC_ALL set to C)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
Versions of packages dash depends on:
ii debianutils 4.4+b1
ii dpkg 1.17.27
ii libc6 2.19-18+deb8u6
dash recommends no packages.
dash suggests no packages.
-- debconf information:
* dash/sh: true
