Red Hat NETSCAPE MANAGEMENT SYSTEM 6.0 - COMMAND-LINE Manuale Utente Scaricare il pdf (Pagina 36)

Quote Marks

Regular double quotes ("like these") make the shell ignore whitespace and count it all as one

argument being passed or string to use. Special characters inside are still noticed/obeyed.

Single quotes 'like this' make the interpreting shell ignore all special characters in whatever

string is being passed.

The back single quote marks (`command`) perform a different function. They are used when you

want to use the results of a command in another command. For example, if you wanted to set the

value of the variable contents equal to the list of files in the current directory, you would type the

following command: contents=`ls`, the results of the ls program are put in the variable contents.

Logic and comparisons

A command called test is used to evaluate conditional expressions, such as a if-then statement

that checks the entrance/exit criteria for a loop.

test expression

[ expression ]

Numeric Comparisons

int1 -eq int2 Returns True if int1 is equal to int2.

int1 -ge int2

Returns True if int1 is greater than or equal to

int2.

int1 -gt int2 Returns True if int1 is greater than int2.

int1 -le int2 Returns True if int1 is less than or equal to int2

int1 -lt int2 Returns True if int1 is less than int2

int1 -ne int2 Returns True if int1 is not equal to int2

String Comparisons

str1 = str2 Returns True if str1 is identical to str2.

str1 != str2 Returns True if str1 is not identical to str2.

str Returns True if str is not null.

-n str

Returns True if the length of str is greater than

zero.

-z str

Returns True if the length of str is equal to zero.

(zero is different than null)

File Comparisons

-d filename Returns True if file, filename is a directory.

-f filename Returns True if file, filename is an ordinary file.

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Red Hat NETSCAPE MANAGEMENT SYSTEM 6.0 - COMMAND-LINE Manuale Utente Pagina 36