failure of running ./configure in a2ps-4.13 installation

[wqin]

Hi there,

I downloaded a2ps-4.13b.tar.gz from your web site. After gunzip and tar xvf it, 
I tried to install a2ps by following your instructions in README. But I got the 
following error message whenever running ./configure. It failed and I cannot 
proceed from here. Any suggestions?

My machine (Sun Ultra-10) runs Solaris 7.2. I'd appreciate for your answer.

Wenhan
-------------
loading cache ./config.cache
checking for a BSD compatible install... auxdir/install-sh -c
checking whether build environment is sane... yes
checking for mawk... no
checking for gawk... no
checking for nawk... nawk
checking whether make sets ${MAKE}... yes
checking for mawk... (cached) nawk
checking for gm4... no
checking for gnum4... no
checking for m4... /usr/ccs/bin/m4
checking whether m4 supports frozen files... no
checking for a BSD compatible install... auxdir/install-sh -c
checking whether ln -s works... yes
checking whether make sets ${MAKE}... (cached) yes
checking for perl... /usr/local/bin/perl
checking for gcc... no
checking for cc... /export/home/opt/SUNWspro/bin/cc
checking whether the C compiler (/export/home/opt/SUNWspro/bin/cc   ) works... 
yes
checking whether the C compiler (/export/home/opt/SUNWspro/bin/cc   ) is a 
cross-compiler... no
checking whether we are using GNU C... no
checking whether /export/home/opt/SUNWspro/bin/cc accepts -g... yes
checking how to run the C preprocessor... /export/home/opt/SUNWspro/bin/cc -E
checking dependency style of /export/home/opt/SUNWspro/bin/cc... none
checking for AIX... no
checking for minix/config.h... no
checking for POSIXized ISC... no
checking how to run the C preprocessor... /export/home/opt/SUNWspro/bin/cc -E
checking for /export/home/opt/SUNWspro/bin/cc option to accept ANSI C... none 
needed
checking for function prototypes... yes
checking for bison... no
checking for byacc... no
checking how to suppress newlines using echo... escape
checking for flex... no
checking for lex... no
checking for flex... ${SHELL} 
/export/home/wqin/tmp/tar/misc/gnu/a2ps-4.13/auxdir/missing --run flex
checking for yywrap in -ll... yes
checking lex output file root... ./configure: ${SHELL}: not found
configure: error: cannot find output from ${SHELL} 
/export/home/wqin/tmp/tar/misc/gnu/a2ps-4.13/auxdir/missing --run flex; giving 
up
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