bash unary operator expected

When the centos system is switched from the root user to Oracle, the following message is always displayed:-Bash-: [: unary operator expectedIf the switchover succeeds, the above message is displayed. Later, the reason is found. When installing the

Help. Fedora17-Linux general technology-Linux technology and application information. The following is a detailed description. Bash: [: too many parameters Bash: [: =: Expected unary expression Bash: [: =: Expected unary expression Bash: [: =:

Know when to use a space in bash and when not to use it. 1. Equal value assignment cannot have spaces on either side2. Spaces are required between commands and options3. Pipe on both sides of the space is optional Let's take a look at the common

I used to read some articles and learn more about them. I usually write a simple command combination, but I have never written complex scripts. Recently, I wrote a script to restore the data and found that the optical field does not work properly.

The condition test statement in bash-general Linux technology-Linux technology and application information. The following is a detailed description. [I = s] This post was last edited by yanyongkg at, 2011-8-13 Comparison string: ["string1" =

As operations personnel, often use Linux know, under Linux, a lot of commands, keywords, looks like a long, but the actual application can be found sometimes there is a difference, of course, the person who is not careful perhaps you will never

Conditional expression ("CONDITIONAL EXPRESSIONS") Conditional expressions are used in [composite commands and built-in command test and [to test file properties for string and arithmetic comparisons.] An expression is constructed using the

Compile-language:The program needs a special compilation process before execution, which compiles the program into a machine language file, the runtime does not need to be re-translated, the results of the direct use of the compilation is OK. The

23. Grep/egrep Regular Expression exercises:1) display lines in the/etc/passwd file that do not end with bash;For:# grep-v "bash$"/etc/passwd2) Locate the two-bit or three-bit integer in the result of the ifconfig command execution;For:# Ifconfig |

Test Condition Expression Description File symbols: [Root@lamp test]# Help testtest:test [expr]Evaluate conditional expression.Exits with a status of 0 (True) or 1 (false) depending onThe evaluation of EXPR.  Expressions May is unary or binary.