bash脚本比较运算符和if else和test命令

比较运算符

来自于这个课本：

Advanced Bash-Scripting Guide:

详细参考链接：

Other Comparison Operatorshttps://tldp.org/LDP/abs/html/comparison-ops.html

if Else if and elif

还有test测试命令

详细参考链接：

Test Constructshttps://tldp.org/LDP/abs/html/testconstructs.html#TTESTREF

hl@ubuntu:~$ man test( EXPRESSION )EXPRESSION is true! EXPRESSIONEXPRESSION is falseEXPRESSION1 -a EXPRESSION2both EXPRESSION1 and EXPRESSION2 are trueEXPRESSION1 -o EXPRESSION2either EXPRESSION1 or EXPRESSION2 is true-n STRINGthe length of STRING is nonzeroSTRING equivalent to -n STRING-z STRINGthe length of STRING is zeroSTRING1 = STRING2the strings are equalSTRING1 != STRING2the strings are not equalINTEGER1 -le INTEGER2INTEGER1 is less than or equal to INTEGER2INTEGER1 -lt INTEGER2INTEGER1 is less than INTEGER2INTEGER1 -ne INTEGER2INTEGER1 is not equal to INTEGER2FILE1 -ef FILE2FILE1 and FILE2 have the same device and inode numbersFILE1 -nt FILE2FILE1 is newer (modification date) than FILE2FILE1 -ot FILE2FILE1 is older than FILE2-b FILEFILE exists and is block special-c FILEFILE exists and is character special-d FILEFILE exists and is a directory-e FILEFILE exists-f FILEFILE exists and is a regular file-g FILEFILE exists and is set-group-ID-G FILEFILE exists and is owned by the effective group ID-h FILEFILE exists and is a symbolic link (same as -L)-k FILEFILE exists and has its sticky bit set-L FILEFILE exists and is a symbolic link (same as -h)-O FILEFILE exists and is owned by the effective user ID-p FILEFILE exists and is a named pipe-r FILEFILE exists and read permission is granted-s FILEFILE exists and has a size greater than zero-S FILEFILE exists and is a socket-t FD  file descriptor FD is opened on a terminal-u FILEFILE exists and its set-user-ID bit is set-w FILEFILE exists and write permission is granted-x FILEFILE exists and execute (or search) permission is granted

NOTE: Binary -a and -o are inherently ambiguous. Use 'test EXPR1 && test EXPR2' or 'test EXPR1 || test EXPR2' instead.

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bash脚本比较运算符和if else和test命令

比较运算符

if Else if and elif

还有test测试命令

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