请教emerge时遇到的一个shell语法错误[已解决]

zeyata

今天emerge sudo时遇到一个奇怪的shell语法错误
USE flag参考

1. miqiur@miahiu ~ $ emerge -pv sudo
   
2. 
   
3. These are the packages that would be merged, in order:
   
4. 
   
5. Calculating dependencies... done!
   
6. [ebuild   R   ] app-admin/sudo-1.7.2_p4  USE="ldap pam -offensive (-selinux) -skey" 0 kB
   
7. 
   
8. Total: 1 package (1 reinstall), Size of downloads: 0 kB
   

复制代码

实际运行时输出一行错误提示

1. ./configure: line 21855: test: =: unary operator expected

复制代码

这是在configure时报的错，但错误被忽略了，emerge成功。完了之后我找到源码包/usr/portage/distfiles/sudo-1.7.2p4.tar.gz，cp到~/tmp下解压，并且确定emerge时没有添加patch。于是我找到configure源文件的第21855行

1. if test ${with_skey-'no'} = "yes"; then
   

复制代码

如果条件成立会执行后面跟着的50多行代码

1. 
   
2. if test ${with_AFS-'no'} = "yes"; then
   
3. 
   
4.     # looks like the "standard" place for AFS libs is /usr/afsws/lib
   
5.     AFSLIBDIRS="/usr/lib/afs /usr/afsws/lib /usr/afsws/lib/afs"
   
6.     for i in $AFSLIBDIRS; do
   
7.         if test -d ${i}; then
   
8. 
   
9.     if test X"$with_rpath" = X"yes"; then
   
10.         SUDO_LDFLAGS="${SUDO_LDFLAGS} -L$i -R$i"
    
11.     else
    
12.         SUDO_LDFLAGS="${SUDO_LDFLAGS} -L$i"
    
13.     fi
    
14.     if test X"$blibpath" != X"" -a "SUDO_LDFLAGS" = "SUDO_LDFLAGS"; then
    
15.         blibpath_add="${blibpath_add}:$i"
    
16.     fi
    
17. 
    
18.             FOUND_AFSLIBDIR=true
    
19.         fi
    
20.     done
    
21.     if test -z "$FOUND_AFSLIBDIR"; then
    
22.         { echo "$as_me:$LINENO: WARNING: Unable to locate AFS libraries, you will have to edit the Makefile and add -L/path/to/afs/libs to SUDO_LDFLAGS or rerun configure with the --with-libpath options." >&5
    
23. echo "$as_me: WARNING: Unable to locate AFS libraries, you will have to edit the Makefile and add -L/path/to/afs/libs to SUDO_LDFLAGS or rerun configure with the --with-libpath options." >&2;}
    
24.     fi
    
25. 
    
26.     # Order is important here.  Note that we build AFS_LIBS from right to left
    
27.     # since AFS_LIBS may be initialized with BSD compat libs that must go last
    
28.     AFS_LIBS="-laudit ${AFS_LIBS}"
    
29.     for i in $AFSLIBDIRS; do
    
30.         if test -f ${i}/util.a; then
    
31.             AFS_LIBS="${i}/util.a ${AFS_LIBS}"
    
32.             FOUND_UTIL_A=true
    
33.             break;
    
34.         fi
    
35.     done
    
36.     if test -z "$FOUND_UTIL_A"; then
    
37.         AFS_LIBS="-lutil ${AFS_LIBS}"
    
38.     fi
    
39.     AFS_LIBS="-lkauth -lprot -lubik -lauth -lrxkad -lsys -ldes -lrx -llwp -lcom_err ${AFS_LIBS}"
    
40. 
    
41.     # AFS includes may live in /usr/include on some machines...
    
42.     for i in /usr/afsws/include; do
    
43.         if test -d ${i}; then
    
44.             CPPFLAGS="${CPPFLAGS} -I${i}"
    
45.             FOUND_AFSINCDIR=true
    
46.         fi
    
47.     done
    
48. 
    
49.     if test -z "$FOUND_AFSLIBDIR"; then
    
50.         { echo "$as_me:$LINENO: WARNING: Unable to locate AFS include dir, you may have to edit the Makefile and add -I/path/to/afs/includes to CPPFLAGS or rerun configure with the --with-incpath options." >&5
    
51. echo "$as_me: WARNING: Unable to locate AFS include dir, you may have to edit the Makefile and add -I/path/to/afs/includes to CPPFLAGS or rerun configure with the --with-incpath options." >&2;}
    
52.     fi
    
53. 
    
54.     AUTH_OBJS="$AUTH_OBJS afs.o"
    
55. fi
    
56. 
    

复制代码

但因为这个错误，导致这些代码都没有执行。
但我发现这个错误很奇怪，在交互式bash和交互式sh环境下都无法重现，要想出现这个错误必须是这种形式的代码

1. miqiur@miahiu ~/tmp $ test = "yes"
   
2. -bash: test: =: unary operator expectedtest
   

复制代码

也就是说configure脚本中的

1. test ${with_skey-'no'} = "yes"

复制代码

被解释成

1. test = "yes"

复制代码

但是无论在bash里还是在sh里，不管with_skey变量是否初始化，长度是否为0，${with_skey-'no'}都会被赋值为一个非空非零长的值。
所以我对这个错误一直无法理解。
请教各位，这是为何。
是否和shell的设置有关？
附上configure脚本的前30行，包含一些shell的设置，脚本的其它地方也有，但没细看，太长了

1. miqiur@miahiu ~/tmp/sudo/sudo-1.7.2p4 $ head -30 configure
   
2. #! /bin/sh
   
3. # Guess values for system-dependent variables and create Makefiles.
   
4. # Generated by GNU Autoconf 2.61 for sudo 1.7.2p4.
   
5. #
   
6. # Report bugs to <http://www.sudo.ws/bugs/>.
   
7. #
   
8. # Copyright (C) 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001,
   
9. # 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
   
10. # This configure script is free software; the Free Software Foundation
    
11. # gives unlimited permission to copy, distribute and modify it.
    
12. ## --------------------- ##
    
13. ## M4sh Initialization.  ##
    
14. ## --------------------- ##
    
15. 
    
16. # Be more Bourne compatible
    
17. DUALCASE=1; export DUALCASE # for MKS sh
    
18. if test -n "${ZSH_VERSION+set}" && (emulate sh) >/dev/null 2>&1; then
    
19.   emulate sh
    
20.   NULLCMD=:
    
21.   # Zsh 3.x and 4.x performs word splitting on ${1+"$@"}, which
    
22.   # is contrary to our usage.  Disable this feature.
    
23.   alias -g '${1+"$@"}'='"$@"'
    
24.   setopt NO_GLOB_SUBST
    
25. else
    
26.   case `(set -o) 2>/dev/null` in
    
27.   *posix*) set -o posix ;;
    
28. esac
    
29. 
    
30. fi
    
31. 
    

复制代码

我系统上的/bin/sh是链接到bash的

1. miqiur@miahiu ~/tmp/sudo/sudo-1.7.2p4 $ readlink -f /bin/sh
   
2. /bin/bash

复制代码

zeyata

不好意思，解决了

1. sh-4.0$ zerolength=
   
2. sh-4.0$ test ${zerolength-no} = "yes"
   
3. sh: test: =: unary operator expected
   
4. sh-4.0$ test ${zerolength-:no} = "yes"
   
5. sh: test: =: unary operator expected
   
6. sh-4.0$ echo ${zerolength-no}
   
7. 
   
8. sh-4.0$ echo ${zerolength:-no}
   
9. no
   
10. sh-4.0$ unset zerolength
    
11. sh-4.0$ test ${zerolength-no} = "yes"
    
12. sh-4.0$ test ${zerolength-:no} = "yes"
    
13. sh-4.0$ echo ${zerolength-no}
    
14. no
    
15. sh-4.0$ echo ${zerolength:-no}
    
16. no
    
17. sh-4.0$ zerolength=xxxxx
    
18. sh-4.0$ test ${zerolength-no} = "yes"
    
19. sh-4.0$ test ${zerolength-:no} = "yes"
    
20. sh-4.0$ echo ${zerolength-no}
    
21. xxxxx
    
22. sh-4.0$ echo ${zerolength:-no}
    
23. xxxxx
    
24. sh-4.0$ zerolength=
    
25. sh-4.0$ test "${zerolength-no}" = "yes"
    
26. sh-4.0$ test "${zerolength-:no}" = "yes"
    
27. sh-4.0$ echo "${zerolength-no}"
    
28. 
    
29. sh-4.0$ echo "${zerolength:-no}"
    
30. no
    

复制代码

得加上双引号才能避免这种错误