[ian@pinguino ~]$ test 3 -gt 4 && echo True || echo falsefalse[ian@pinguino ~]$ [ "abc" != "def" ];echo $?0[ian@pinguino ~]$ test -d "$HOME" ;echo $?0 |
[ian@pinguino ~]$ test "abc" = "def" ;echo $?1[ian@pinguino ~]$ [ "abc" != "def" ];echo $?0[ian@pinguino ~]$ [ "abc" \< "def" ];echo $?0[ian@pinguino ~]$ [ "abc" \> "def" ];echo $?1[ian@pinguino ~]$ [ "abc" \<"abc" ];echo $?1[ian@pinguino ~]$ [ "abc" \> "abc" ];echo $?1 |
[ian@pinguino ~]$ set +o nounset[ian@pinguino ~]$ [ -o nounset ];echo $?1[ian@pinguino ~]$ set -u[ian@pinguino ~]$ test -o nounset; echo $?0 |
[ian@pinguino ~]$ test "a" != "$HOME" -a 3 -ge 4 ; echo $?1[ian@pinguino ~]$ [ ! \( "a" = "$HOME" -o 3 -lt 4 \) ]; echo $?1[ian@pinguino ~]$ [ ! \( "a" = "$HOME" -o '(' 3 -lt 4 ')' ")" ]; echo $?1 |
[ian@pinguino ~]$ let x=2 y=2**3 z=y*3;echo $? $x $y $z0 2 8 24[ian@pinguino ~]$ (( w=(y/x) + ( (~ ++x) & 0x0f ) )); echo $? $x $y $w0 3 8 16[ian@pinguino ~]$ (( w=(y/x) + ( (~ ++x) & 0x0f ) )); echo $? $x $y $w0 4 8 13 |
[ian@pinguino ~]$ [[ ( -d "$HOME" ) && ( -w "$HOME" ) ]] && > echo "home is a writable directory"home is a writable directory |
欢迎光临 电子技术论坛_中国专业的电子工程师学习交流社区-中电网技术论坛 (http://bbs.eccn.com/) | Powered by Discuz! 7.0.0 |