Linux Command Line and Shell Scripting Bible

A terminal is a user interface, while a shell is running inside a terminal. Early Terminals Ear...

A shell is a command-line interpreter that lets you interact with the operating system by typing ...

The Mysterious ^[[A First, start a new Shell /bin/sh. /bin/sh Then enter the following command,...

Default Shell echo $SHELL /bin/bash If you start a new Shell in the current terminal (e.g., sw...

Builtin Commands Builtin commands are implemented by the Shell itself, they run without starting...

Shell variables are a general term. If you are using a specific shell, such as Bash, you can call...

The definition of Subshell in some books or materials is unclear, and the explanations often cont...

MAN This command can view different sections of the manual pages. man man man - an interface to...

Sort Sorts lines of text files by default, non-numeric. sort - sort lines of text files Reverse...

Full name Global Regular Expression Print, originated from a Unix editor ed command g/re/p, where...

PS stands for Process Status. man ps ps - report a snapshot of the current processes. Style ...

man top top - display Linux processes The top command defaults to sorting processes by CPU usag...

Kill Command It's actually a tool for sending signals to processes, not necessarily killing them...

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Origins The environment variables in Linux originated from the design requirements of early UNIX...

Startup Methods The startup methods of Shell will affect the loading process of environment vari...

SHELL The current shell in use. printenv SHELL /bin/bash HOME The path to the user's home dir...

Shebang is a special symbol in Unix and Unix-like operating systems, composed of the characters #...

Account /etc/passwd Linux uses the /etc/passwd file to store user account information. Because m...

Relationship Primary Group When a user is created, a group with the same name is also created, w...

Composition Structure -rwxr-xr-- The first character indicates the file type: -：File, such as ...

Access Control List (ACL) is a more flexible and fine-grained permission management mechanism, us...

The first process of the system, with a process ID of 1. ps -p 1 PID TTY TIME CMD 1 ?...

Basic Concepts A file descriptor (FD) is an integer identifier used to represent an open file or...

Basic Concepts A pipe can use the output of one command as the input of the next command, repres...

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File System Types You can use the -T option of the df command to view the Type field. df -Th Fi...

Shebang #!/usr/bin/env bash Variable Assignment No spaces are allowed around the = sign. name=...

If Statement If the exit code of command is 0, then execute the content of then. if command then...

For Statement for var in list do ... done The var variable can be normally used outside the...

Positional Parameters Positional Parameters, script positional parameters. $0: script name, inc...

Standard File Descriptors Standard File Descriptors. Name Number Description STDIN 0 Stan...

Bash Shell By default, the Bash Shell ignores the SIGQUIT(3) and SIGTERM(15) signals, so executi...

Creating a Function function name { commands } or name() { commands } Function Return...

In Bash, parameter expansion is a mechanism for manipulating and handling the contents of variabl...

Parameters: $? The exit code of the previous command or script, 0 for success, non-0 for failure...

Echo Command Using the -e option can create simple multi-line text. echo -e 'aa\nbb' aa bb He...

Regular Expressions (regex) can be divided into the following categories based on different stand...

Stream Editor, a stream text processor, authored by Lee E. McMahon. Basic Syntax sed [OPTIONS] 'c...

Gnu Awk Gawk is the GNU version of the text processing tool. In most GNU/Linux distributions, Ga...

Regular Expression gawk defaults to using ERE mode. Basic Usage First, create the foo text file....

hassle-free 无麻烦的，省心的。 Go compiles to a single, static binary with minimal runtime dependencies, ...