在编译Linux内核时出现错误：
wit@ubuntu:/home/linux-5.4.14# make vexpress_defconfig
LEX scripts/kconfig/lexer.lex.c
/bin/sh: 1: flex: not found
make[1]: *** [scripts/Makefile.host:9: scripts/kconfig/lexer.lex.c] Error 127
make: *** [Makefile:568: vexpress_defconfig] Error 2
wit@ubuntu:/home/linux-5.4.14# make menuconfig
UPD scripts/kconfig/mconf-cfg
HOSTCC scripts/kconfig/mconf.o
HOSTCC scripts/kconfig/lxdialog/checklist.o
HOSTCC scripts/kconfig/lxdialog/inputbox.o
HOSTCC scripts/kconfig/lxdialog/menubox.o
HOSTCC scripts/kconfig/lxdialog/textbox.o
HOSTCC scripts/kconfig/lxdialog/util.o
HOSTCC scripts/kconfig/lxdialog/yesno.o
LEX scripts/kconfig/lexer.lex.c
/bin/sh: 1: flex: not found
make[1]: *** [scripts/Makefile.host:9: scripts/kconfig/lexer.lex.c] Error 127
make: *** [Makefile:568: menuconfig] Error 2
解决方法：分别安装词法解析器flex，和语法解析器bison：
# apt install flex
# pt install bison
