From: deanw
To: [email protected]
Subject: Backslashed space in variable expansion does not prevent splitting.
Configuration Information [Automatically generated, do not change]:
Machine: i686 OS: cygwin Compiler: gcc Compilation CFLAGS: -
DPROGRAM='bash.exe' -DCONF_HOSTTYPE='i686' -DCONF_OSTYPE='cygwin'
-DCONF_MACHTYPE='i686-pc-
cygwin' -DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -
DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H -DRECYCLES_PIDS -I.
-I/usr/src/bash-4.3.42-4.i686/src/bash-
4.3 -I/usr/src/bash-4.3.42-4.i686/src/bash-4.3/include
-I/usr/src/bash-4.3.42-4.i686/src/bash-
4.3/lib -DWORDEXP_OPTION -ggdb -O2 -pipe -Wimplicit-function-
declaration -fdebug-prefix-map=/usr/src/bash-4.3.42-
4.i686/build=/usr/src/debug/bash-4.3.42-4
-fdebug-prefix-map=/usr/src/bash-4.3.42-4.i686/src/bash-
4.3=/usr/src/debug/bash-4.3.42-4 uname output: CYGWIN_NT-6.1-WOW
DW03PC02 2.5.1(0.297/5/3) 2016-04-21 22:12 i686 Cygwin Machine Type:
i686-pc-cygwin
Bash Version: 4.3 Patch Level: 42 Release Status: release
Description:
The expansion of a variable containing spaces splits on all spaces including
escaped/backslashed space.
I ran into this problem when trying to buiild a TCL extension. Building
the extension requires pulling in with source tclConfig.sh which
provides various settings. TCL_DEFS contains space separated -D
arguments to pass to gcc. Some of these arguements contains space
which are backslashed to prevent splitting.
Argument expansion is not distinguishing between space and backslased
space. I have tried 3.00.16(1)-release on FedoraCore 4, 4.2.10(1)-
release on FedoraCore 16, 4.3.42(4)-release on Cygwin 2.5.1 with the
same outcome.
Repeat-By:
Run the ./bad_exp.sh script. It explains the desired behaviour and
demonstrates issue. I include below the contents of two script and my output
log.
=====Start File ./bad_exp.sh
#!/usr/bin/env bash
# Issue: Backslash space is not preventing argument splitting
echo $BASH_VERSION
# TCL_DEFS is actually source-d from TCL config script so have no
# control over it.
TCL_DEFS='-DPACKAGE_NAME=\"tcl\" -DPACKAGE_TARNAME=\"tcl\" -
DPACKAGE_VERSION=\"8.5\" -DPACKAGE_STRING=\"tcl\ 8.5\" -
DPACKAGE_BUGREPORT=\"\" -DSTDC_HEADERS=1 -DHAVE_SYS_TYPES_H=1 -
DHAVE_SYS_STAT_H=1 -DHAVE_STDLIB_H=1 -DHAVE_STRING_H=1 -
DHAVE_MEMORY_H=1 -DHAVE_STRINGS_H=1 -DHAVE_INTTYPES_H=1 -
DHAVE_STDINT_H=1 -DHAVE_UNISTD_H=1 -DHAVE_LIMITS_H=1 -
DHAVE_SYS_PARAM_H=1 -DTCL_CFGVAL_ENCODING=\"iso8859-1\" -
DMODULE_SCOPE=extern\ __attribute__\(\(__visibility__\(\"hidden\"\)\)\)
-DTCL_CFG_DO64BIT=1 -DHAVE_CAST_TO_UNION=1 -DTCL_SHLIB_EXT=\".so\" -
DNDEBUG=1 -DTCL_CFG_OPTIMIZED=1 -DTCL_TOMMATH=1 -DMP_PREC=4 -
D_LARGEFILE64_SOURCE=1 -DTCL_WIDE_INT_IS_LONG=1 -DHAVE_GETCWD=1 -
DHAVE_OPENDIR=1 -DHAVE_STRTOL=1 -DHAVE_WAITPID=1 -DHAVE_GETADDRINFO=1
-DUSE_TERMIOS=1 -DHAVE_SYS_TIME_H=1 -DTIME_WITH_SYS_TIME=1 -
DHAVE_GMTIME_R=1 -DHAVE_LOCALTIME_R=1 -DHAVE_MKTIME=1 -
DHAVE_TM_GMTOFF=1 -DHAVE_TIMEZONE_VAR=1 -DHAVE_STRUCT_STAT_ST_BLOCKS=1
-DHAVE_STRUCT_STAT_ST_BLKSIZE=1 -DHAVE_BLKCNT_T=1 -DHAVE_INTPTR_T=1 -
DHAVE_UINTPTR_T=1 -DHAVE_SIGNED_CHAR=1 -DHAVE_LANGINFO=1 -
DHAVE_SYS_IOCTL_H=1 -DTCL_UNLOAD_DLLS=1 -DHAVE_CPUID=1 '
./echo_args.sh ${TCL_DEFS}
echo 'Reduction of problem' echo 'The desired result is echo_args should
receive three arguments arg0, arg1 and "arg 2"' T='arg0 arg1 arg\ 2'
echo 'This receives four arguments, wrongly splitting on the backslashed
space' ./echo_args.sh $T
echo 'This correctly receives one argument but is not the desired
result' ./echo_args.sh "$T"
=====End File ./bad_exp.sh =Start File echo_args.sh
#!/usr/bin/env bash
# Script to display command line arguments
echo "${#} arguments" i=0 for arg in "${@}" do echo "${i}:$arg"
((i++)) done
=====End File echo_args.sh =Start output log
4.2.10(1)-release 53 arguments :-DPACKAGE_NAME=\"tcl\"
1:-DPACKAGE_TARNAME=\"tcl\"
2:-DPACKAGE_VERSION=\"8.5\"
3:-DPACKAGE_STRING=\"tcl\
4:8.5\"
5:-DPACKAGE_BUGREPORT=\"\"
6:-DSTDC_HEADERS=1
7:-DHAVE_SYS_TYPES_H=1
8:-DHAVE_SYS_STAT_H=1
9:-DHAVE_STDLIB_H=1
10:-DHAVE_STRING_H=1
11:-DHAVE_MEMORY_H=1
12:-DHAVE_STRINGS_H=1
13:-DHAVE_INTTYPES_H=1
14:-DHAVE_STDINT_H=1
15:-DHAVE_UNISTD_H=1
16:-DHAVE_LIMITS_H=1
17:-DHAVE_SYS_PARAM_H=1
18:-DTCL_CFGVAL_ENCODING=\"iso8859-1\"
19:-DMODULE_SCOPE=extern\
20:__attribute__\(\(__visibility__\(\"hidden\"\)\)\)
21:-DTCL_CFG_DO64BIT=1
22:-DHAVE_CAST_TO_UNION=1
23:-DTCL_SHLIB_EXT=\".so\"
24:-DNDEBUG=1
25:-DTCL_CFG_OPTIMIZED=1
26:-DTCL_TOMMATH=1
27:-DMP_PREC=4
28:-D_LARGEFILE64_SOURCE=1
29:-DTCL_WIDE_INT_IS_LONG=1
30:-DHAVE_GETCWD=1
31:-DHAVE_OPENDIR=1
32:-DHAVE_STRTOL=1
33:-DHAVE_WAITPID=1
34:-DHAVE_GETADDRINFO=1
35:-DUSE_TERMIOS=1
36:-DHAVE_SYS_TIME_H=1
37:-DTIME_WITH_SYS_TIME=1
38:-DHAVE_GMTIME_R=1
39:-DHAVE_LOCALTIME_R=1
40:-DHAVE_MKTIME=1
41:-DHAVE_TM_GMTOFF=1
42:-DHAVE_TIMEZONE_VAR=1
43:-DHAVE_STRUCT_STAT_ST_BLOCKS=1
44:-DHAVE_STRUCT_STAT_ST_BLKSIZE=1
45:-DHAVE_BLKCNT_T=1
46:-DHAVE_INTPTR_T=1
47:-DHAVE_UINTPTR_T=1
48:-DHAVE_SIGNED_CHAR=1
49:-DHAVE_LANGINFO=1
50:-DHAVE_SYS_IOCTL_H=1
51:-DTCL_UNLOAD_DLLS=1
52:-DHAVE_CPUID=1 Reduction of problem The desired result is echo_args
should receive three arguments arg0, arg1 and "arg 2" This receives
four arguments, wrongly splitting on the backslashed space 4
arguments :arg0
1:arg1
2:arg\
3:2 This correctly receives one argument but is not the desired result
1 arguments :arg0 arg1 arg\ 2
=====End output log
