"Shell" conditional judgment

expression format for conditional judgments:

File Judging type:

[[Email protected] ~]# [-E/ROOT/1] && echo yes | | echo no  #注意 [] inside the space, the first command is true print Yes, otherwise print noyes[[email protected] ~]# [-F/ROOT/1] && echo yes | | Echo no   yes[ [Email protected] ~]# [-D/ROOT/1] && echo yes | | Echo No No

File permission to determine the type:

[[Email protected] ~]# [-R/ROOT/1] && echo yes | | echo no yes[[email protected] ~]# [-X/ROOT/1] && echo yes | | echo no no[[email protected] ~]# [-W/ROOT/1] && echo yes | | Echo No Yes

File comparison and judgement type:

[[Email protected] ~]# [  /root/1-NT/ROOT/2] && echo yes | | echo no no[[email protected] ~]# [  /ROOT/1- OT/ROOT/2] && echo yes | | echo no yes[[email protected] ~]# [  /root/1-EF/ROOT/2] && echo yes | | echo no no[[email protected] ~]# ln
   1  3[[email protected] ~]# [  /root/1-EF/ROOT/3] && echo yes | | Echo No Yes

　Integer comparison judgment:

[[Email protected] ~]# [4-eq 4] && echo yes | | echo No  #等于yes [[email protected] ~]# [4-ne 4] && echo yes | | echo no  # #不等于no [[email protected] ~]# [5 -GT 4] && echo yes | | Echo No  # #大于yes [[email protected] ~]# [5-LT 4] && echo yes | | echo no  # #小于no [[email protected] ~]# [5 -ge 4] && echo yes | | Echo No   # #大于等于yes [[email protected] ~]# [5-le 4] && echo yes | | echo no  # #小于等于no

String-Judging:

[[Email protected] ~]# [-Z $a] && echo yes | | Echo No  # #判断为空no [[email protected] ~]# [-n $a] && echo yes | | echo no  # #判断非空yes [[email protected] ~]# b= Abc[[email protected] ~]# [$a = = $b] && echo yes | | echo Noyes[[email protected] ~]# [$a! = $b] && echo yes | | Echo Nono

Multi-Conditional judgment:

[[Email protected] ~]# [-N $b-Z $a] && echo yes | | Echo No  # #与no [[email protected] ~]# [-N $b-O-Z $a] && echo yes | | echo no  # #或yes

　　

"Shell" conditional judgment