Shulou(Shulou.com)06/03 Report--

If

Syntax: help if

If COMMANDS; then COMMANDS; [elif COMMANDS; then COMMANDS;]... [else COMMANDS;] fi

File related:

1. If [- f file]: whether to ask the file (return false does not exist)

2. If [- d dir]: whether it is a directory

3. If [- e file]: whether the file (directory) exists

4. If [- r file]: whether it is readable

5. If [- w file]: whether it is writable

6. If [- x file]: whether it is executable

7. If [- s file]: whether it is an empty file

8. If [- S file]: whether it is a Socket file

Compare size (integer variable)

1. If [a-eq b]: whether it is equal or not

2. If [a-ne b]: whether it is different or not

3. If [a-ge b]: greater than or equal to

4. If [a-gt b]: greater than

5. If [a-le b]: less than or equal to

6. If [a-lt b]: less than

String comparison

1. If [a = b]: whether it is equal

2. If [a! = b]: whether it is unequal

3. If [- n str]: non-empty

4. If [- z str]: empty

5. If [str]: non-empty, similar to-n

Logical operation (not yet verified)

1 、 if [! Exp]: not

2. If [!-d $dir]: directory does not exist

3. If [exp1-an exp2]: and

4. If [exp1-o exp2]: or

For

Syntax: help for

For ((exp1; exp2; exp3)); do COMMANDS; done

For NAME [in WORDS...]; do COMMANDS; done

Example:

For ((iTuno; I

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