Bash Shell Basic Features II

Bash Shell Basic Features II

(1) globbing

Text name wildcard: Meta characters

*: matches any character of any length;

?: matches any single character;

Example: A*b:aab, AB, a123b;

A?b:

[]: matches any single character within the specified range;

Example: [0-9]

[^]: matches any single character outside the range;

Example: [^a-b]

Character Set:

[: Lower:] matches lowercase letters. Equivalent to A-Z

[: Upper:] matches uppercase letters. Equivalent to A-Z

[: Alnum:] matches letters and numbers. Equivalent to a-za-z0-9

[:d Igit:] Matches (decimal) number. Equivalent to 0-9

[: Space:] matches white space characters (whitespace and horizontal tabs)

[:p UNCT:] Match symbol

[: Alnum:] matches letters and numbers. Equivalent to a-za-z0-9

Example:

Display/etc/directory, beginning with a non-letter, followed by a letter and any other arbitrary length of any character file or directory;

ls/etc/[^a-z][a-z]*

Copy all files or directories ending with. D in the/etc directory to the/tmp/mageedu.com directory;

Cp-r/etc/*.d/tmp/mageedu.com

(2) shortcut keys, combination keys

Ctrl+l: Clear Screen

CTRL + A: switch to the beginning of the command

Ctrl+e: Switch to the end of the command line

CTRL + C: Cancel command execution

Ctrl+u: Deletes the contents of the cursor at the beginning of the line;

Ctrl+k: Delete the contents of the cursor at the end of the line;

(3) IO input/output redirection and piping

Program: Instruction + data

Read-in data: Input

Outputs data: Output

The open files are all a Fd:file descriptor

Standard input: Keyboard, 0,/dev/stdin

Standard output: Monitor, 1,/dev/stdout

Standard error Output: monitor, 2,/dev/stderr

Output redirection:, >>//format: command > New_pos, command >> New_po

: The original content in the target file will be erased;

>>: New content is appended to the end of the target file;

# set-c: Prohibit use of overwrite output redirection

You can still use >| to force overwrite

# set +c

Error output redirect: 2>, 2>>

2>: Overwrite

2>>: Append

Redirect both the standard output stream and the error output stream at the same time:

Example:

COMMAND >/path/to/file.out 2>/path/to/file.err

Merge the data flow of standard output and error output to the same place: &>, &>>

&>

&>>

Example:

COMMAND >/path/to/file.out 2>&1

COMMAND &>/path/to/file.out

Enter redirection:

<

TR command: Convert or delete characters

Syntax format: TR [OPTION] ... SET1 [SET2]

Common parameters:

-D: Delete characters

Here document:<<

# Cat << EOF

# cat > file name << EOF

(4) Pipeline: Connect command, implement the output of the previous command as input to the latter command

COMMAND1 | COMMAND2 | ...

Example:

Converts the first two messages logged to all users on the current system to uppercase output;

# who | head-2 | Tr ' A-Z ' A-Z

This article is from the "10,000-hour Law" blog, be sure to keep this source http://daisywei.blog.51cto.com/7837970/1687817

Bash Shell Basic Features II