GNU Bourne-Again Shell (bash 4.4) 用户手册

需积分: 17 89 浏览量更新于2024-07-18 收藏 740KB PDF 举报

"这是关于Bash 4.4版本的手册页转换为PDF的资源，包含了Bash shell的详细信息和使用方法。" Bash 4.4是GNU Bourne-Again SHell的一个版本，它是Linux操作系统中最常用的命令行解释器。Bash不仅兼容传统的Bourne shell（sh），还吸取了Korn shell (ksh)和C shell (csh)的许多有用特性，提供了更丰富的功能和交互性。 **名称** bash — GNU Bourne-Again SHell **概述** Bash可以执行从标准输入或文件读取的命令。它旨在符合IEEE POSIX标准1003.1中的Shell和Utilities部分。通过配置，Bash可以在默认情况下遵循POSIX标准。 **选项** 当启动Bash时，可以使用各种单字符选项。除了在内置命令描述中列出的选项外，Bash还识别以下选项： - `-c`：如果使用-c选项，命令将从第一个非选项参数`command_string`读取。如果`command_string`之后还有其他参数，第一个参数将被赋值给`$0`，剩余的参数则分配给位置参数。`$0`的设置会影响shell的名称，这在警告和错误消息中会显示出来。 **版权** Bash自1989年至2016年版权归Free Software Foundation, Inc.所有。 **描述** Bash支持命令历史、命令别名、文件名扩展、流程控制结构（如if、while、for循环和case语句）、函数定义、环境变量管理以及与系统调用和C库函数类似的内置命令，如cd、echo、export、printf等。 **命令历史** Bash提供了一种机制来保存和重用过去的命令，用户可以通过上下箭头键浏览并重新执行历史记录中的命令。 **文件名扩展** Bash可以自动扩展通配符（如*和?）以匹配文件名，但可以通过设置`set`命令的选项来改变此行为。 **位置参数和特殊变量** Bash提供了位置参数（例如$1, $2等）来访问命令行参数，并有特殊变量如$#, $@, $$等用于表示参数的数量、列表以及进程ID。 **函数** 用户可以定义自己的函数，使复杂的命令序列可重用。 **壳程序脚本** Bash可以执行包含一系列命令的脚本文件，通常以`.sh`扩展名结束。脚本文件可以包含变量赋值、条件测试、循环和其他控制结构。 **提示符** Bash允许用户自定义命令提示符，通过修改PS1环境变量实现。 **作业控制** Bash支持后台进程的管理和恢复，允许用户在不关闭shell的情况下启动进程并在需要时恢复它们。 **信号处理** Bash提供了对Unix信号的支持，允许用户为特定信号定义处理程序。 **国际化与本地化** Bash支持多语言环境，包括对字符编码、日期格式等的处理。 Bash 4.4手册页PDF是一个全面的参考指南，包含了Bash的所有核心特性和用法，对于编写shell脚本和进行命令行操作的用户来说非常有价值。

BASH(1) BASH(1)

HOSTTYPE

Automatically set to a string that uniquely describes the type of machine on which bash is execut-

ing. The default is system-dependent.

LINENO

Each time this parameter is referenced, the shell substitutes a decimal number representing the

current sequential line number (starting with 1) within a script or function. When not in a script or

function, the value substituted is not guaranteed to be meaningful. If LINENO is unset, it loses its

special properties, even if it is subsequently reset.

MACHTYPE

Automatically set to a string that fully describes the system type on which bash is executing, in

the standard GNU cpu-company-system format. The default is system-dependent.

MAPFILE

An array variable (see Arrays below) created to hold the text read by the mapﬁle builtin when no

variable name is supplied.

OLDPWD

The previous working directory as set by the cd command.

OPTARG

The value of the last option argument processed by the getopts builtin command (see SHELL

BUILTIN COMMANDS

below).

OPTIND

The index of the next argument to be processed by the getopts builtin command (see SHELL

BUILTIN COMMANDS

below).

OSTYPE

Automatically set to a string that describes the operating system on which bash is executing. The

default is system-dependent.

PIPESTATUS

An array variable (see Arrays below) containing a list of exit status values from the processes in

the most-recently-executed foreground pipeline (which may contain only a single command).

PPID The process ID of the shell’s parent. This variable is readonly.

PWD The current working directory as set by the cd command.

RANDOM

Each time this parameter is referenced, a random integer between 0 and 32767 is generated. The

sequence of random numbers may be initialized by assigning a value to RANDOM. If RANDOM is

unset, it loses its special properties, even if it is subsequently reset.

READLINE_LINE

The contents of the readline line buffer, for use with bind -x (see SHELL BUILTIN COM-

MANDS

below).

READLINE_POINT

The position of the insertion point in the readline line buffer, for use with bind -x (see SHELL

BUILTIN COMMANDS

below).

Set to the line of input read by the read builtin command when no arguments are supplied.

SECONDS

Each time this parameter is referenced, the number of seconds since shell invocation is returned.

If a value is assigned to SECONDS, the value returned upon subsequent references is the number

of seconds since the assignment plus the value assigned. If SECONDS is unset, it loses its special

properties, even if it is subsequently reset.

SHELLOPTS

A colon-separated list of enabled shell options. Each word in the list is a valid argument for the

−o option to the set builtin command (see SHELL BUILTIN COMMANDS below). The options

appearing in SHELLOPTS are those reported as on by set −o. If this variable is in the environment

when bash starts up, each shell option in the list will be enabled before reading any startup ﬁles.

This variable is read-only.

GNU Bash 4.4 2016 August 26 13

BASH(1) BASH(1)

SHLVL

Incremented by one each time an instance of bash is started.

UID Expands to the user ID of the current user, initialized at shell startup. This variable is readonly.

The following variables are used by the shell. In some cases, bash assigns a default value to a variable;

these cases are noted below.

BASH_COMPAT

The value is used to set the shell’s compatibility level. See the description of the shopt builtin

below under SHELL BUILTIN COMMANDS for a description of the various compatibility lev-

els and their effects. The value may be a decimal number (e.g., 4.2) or an integer (e.g., 42) corre-

sponding to the desired compatibility level. If BASH_COMPAT is unset or set to the empty

string, the compatibility level is set to the default for the current version. If BASH_COMPAT is

set to a value that is not one of the valid compatibility levels, the shell prints an error message and

sets the compatibility level to the default for the current version. The valid compatibility levels

correspond to the compatibility options accepted by the shopt builtin described below (for exam-

ple, compat42 means that 4.2 and 42 are valid values). The current version is also a valid value.

BASH_ENV

If this parameter is set when bash is executing a shell script, its value is interpreted as a ﬁlename

containing commands to initialize the shell, as in ˜/.bashrc. The value of BASH_ENV is subjected

to parameter expansion, command substitution, and arithmetic expansion before being interpreted

as a ﬁlename. PATH is not used to search for the resultant ﬁlename.

BASH_XTRACEFD

If set to an integer corresponding to a valid ﬁle descriptor, bash will write the trace output gener-

ated when set -x is enabled to that ﬁle descriptor. The ﬁle descriptor is closed when

BASH_XTRACEFD is unset or assigned a new value. Unsetting BASH_XTRACEFD or assigning it

the empty string causes the trace output to be sent to the standard error. Note that setting

BASH_XTRACEFD to 2 (the standard error ﬁle descriptor) and then unsetting it will result in the

standard error being closed.

CDPATH

The search path for the cd command. This is a colon-separated list of directories in which the

shell looks for destination directories speciﬁed by the cd command. A sample value is

".:˜:/usr".

CHILD_MAX

Set the number of exited child status values for the shell to remember. Bash will not allow this

value to be decreased below a POSIX-mandated minimum, and there is a maximum value (cur-

rently 8192) that this may not exceed. The minimum value is system-dependent.

COLUMNS

Used by the select compound command to determine the terminal width when printing selection

lists. Automatically set if the checkwinsize option is enabled or in an interactive shell upon

receipt of a SIGWINCH.

COMPREPLY

An array variable from which bash reads the possible completions generated by a shell function

invoked by the programmable completion facility (see Programmable Completion below). Each

array element contains one possible completion.

EMACS

If bash ﬁnds this variable in the environment when the shell starts with value t, it assumes that the

shell is running in an Emacs shell buffer and disables line editing.

ENV Similar to BASH_ENV; used when the shell is invoked in POSIX mode.

EXECIGNORE

A colon-separated list of shell patterns (see Pattern Matching) deﬁning the list of ﬁlenames to be

ignored by command search using PATH. Files whose full pathnames match one of these patterns

are not considered executable ﬁles for the purposes of completion and command execution via

PATH lookup. This does not affect the behavior of the [, test, and [[ commands. Full pathnames

in the command hash table are not subject to EXECIGNORE. Use this variable to ignore shared

library ﬁles that have the executable bit set, but are not executable ﬁles. The pattern matching

GNU Bash 4.4 2016 August 26 14

BASH(1) BASH(1)

honors the setting of the extglob shell option.

FCEDIT

The default editor for the fc builtin command.

FIGNORE

A colon-separated list of sufﬁxes to ignore when performing ﬁlename completion (see READLINE

below). A ﬁlename whose sufﬁx matches one of the entries in FIGNORE is excluded from the list

of matched ﬁlenames. A sample value is ".o:˜".

FUNCNEST

If set to a numeric value greater than 0, deﬁnes a maximum function nesting level. Function

invocations that exceed this nesting level will cause the current command to abort.

GLOBIGNORE

A colon-separated list of patterns deﬁning the set of ﬁlenames to be ignored by pathname expan-

sion. If a ﬁlename matched by a pathname expansion pattern also matches one of the patterns in

GLOBIGNORE, it is removed from the list of matches.

HISTCONTROL

A colon-separated list of values controlling how commands are saved on the history list. If the list

of values includes ignorespace, lines which begin with a space character are not saved in the his-

tory list. A value of ignoredups causes lines matching the previous history entry to not be saved.

A value of ignoreboth is shorthand for ignorespace and ignoredups. A value of erasedups causes

all previous lines matching the current line to be removed from the history list before that line is

saved. Any value not in the above list is ignored. If HISTCONTROL is unset, or does not include

a valid value, all lines read by the shell parser are saved on the history list, subject to the value of

HISTIGNORE. The second and subsequent lines of a multi-line compound command are not

tested, and are added to the history regardless of the value of HISTCONTROL.

HISTFILE

The name of the ﬁle in which command history is saved (see HISTORY below). The default value

is ˜/.bash_history. If unset, the command history is not saved when a shell exits.

HISTFILESIZE

The maximum number of lines contained in the history ﬁle. When this variable is assigned a

value, the history ﬁle is truncated, if necessary, to contain no more than that number of lines by

removing the oldest entries. The history ﬁle is also truncated to this size after writing it when a

shell exits. If the value is 0, the history ﬁle is truncated to zero size. Non-numeric values and

numeric values less than zero inhibit truncation. The shell sets the default value to the value of

HISTSIZE after reading any startup ﬁles.

HISTIGNORE

A colon-separated list of patterns used to decide which command lines should be saved on the his-

tory list. Each pattern is anchored at the beginning of the line and must match the complete line

(no implicit ‘*’ is appended). Each pattern is tested against the line after the checks speciﬁed by

HISTCONTROL are applied. In addition to the normal shell pattern matching characters, ‘&’

matches the previous history line. ‘&’ may be escaped using a backslash; the backslash is

removed before attempting a match. The second and subsequent lines of a multi-line compound

command are not tested, and are added to the history regardless of the value of HISTIGNORE.

The pattern matching honors the setting of the extglob shell option.

HISTSIZE

The number of commands to remember in the command history (see HISTORY below). If the

value is 0, commands are not saved in the history list. Numeric values less than zero result in

ev ery command being saved on the history list (there is no limit). The shell sets the default value

to 500 after reading any startup ﬁles.

HISTTIMEFORMAT

If this variable is set and not null, its value is used as a format string for strftime(3) to print the

time stamp associated with each history entry displayed by the history builtin. If this variable is

set, time stamps are written to the history ﬁle so they may be preserved across shell sessions. This

uses the history comment character to distinguish timestamps from other history lines.

GNU Bash 4.4 2016 August 26 15

BASH(1) BASH(1)

HOME

The home directory of the current user; the default argument for the cd builtin command. The

value of this variable is also used when performing tilde expansion.

HOSTFILE

Contains the name of a ﬁle in the same format as /etc/hosts that should be read when the shell

needs to complete a hostname. The list of possible hostname completions may be changed while

the shell is running; the next time hostname completion is attempted after the value is changed,

bash adds the contents of the new ﬁle to the existing list. If HOSTFILE is set, but has no value, or

does not name a readable ﬁle, bash attempts to read /etc/hosts to obtain the list of possible host-

name completions. When HOSTFILE is unset, the hostname list is cleared.

IFS The Internal Field Separator that is used for word splitting after expansion and to split lines into

words with the read builtin command. The default value is ‘‘<space><tab><newline>’’.

IGNOREEOF

Controls the action of an interactive shell on receipt of an EOF character as the sole input. If set,

the value is the number of consecutive EOF characters which must be typed as the ﬁrst characters

on an input line before bash exits. If the variable exists but does not have a numeric value, or has

no value, the default value is 10. If it does not exist, EOF signiﬁes the end of input to the shell.

INPUTRC

The ﬁlename for the readline startup ﬁle, overriding the default of ˜/.inputrc (see READLINE

below).

LANG Used to determine the locale category for any category not speciﬁcally selected with a variable

starting with LC_.

LC_ALL

This variable overrides the value of LANG and any other LC_ variable specifying a locale cate-

gory.

LC_COLLATE

This variable determines the collation order used when sorting the results of pathname expansion,

and determines the behavior of range expressions, equivalence classes, and collating sequences

within pathname expansion and pattern matching.

LC_CTYPE

This variable determines the interpretation of characters and the behavior of character classes

within pathname expansion and pattern matching.

LC_MESSAGES

This variable determines the locale used to translate double-quoted strings preceded by a $.

LC_NUMERIC

This variable determines the locale category used for number formatting.

LC_TIME

This variable determines the locale category used for data and time formatting.

LINES Used by the select compound command to determine the column length for printing selection lists.

Automatically set if the checkwinsize option is enabled or in an interactive shell upon receipt of a

SIGWINCH.

MAIL If this parameter is set to a ﬁle or directory name and the MAILPATH variable is not set, bash

informs the user of the arrival of mail in the speciﬁed ﬁle or Maildir-format directory.

MAILCHECK

Speciﬁes how often (in seconds) bash checks for mail. The default is 60 seconds. When it is time

to check for mail, the shell does so before displaying the primary prompt. If this variable is unset,

or set to a value that is not a number greater than or equal to zero, the shell disables mail checking.

MAILPATH

A colon-separated list of ﬁlenames to be checked for mail. The message to be printed when mail

arrives in a particular ﬁle may be speciﬁed by separating the ﬁlename from the message with a ‘?’.

When used in the text of the message, $_ expands to the name of the current mailﬁle. Example:

MAILPATH='/var/mail/bfox?"You have mail":˜/shell−mail?"$_ has mail!"'

Bash can be conﬁgured to supply a default value for this variable (there is no value by default), but

the location of the user mail ﬁles that it uses is system dependent (e.g., /var/mail/$USER).

GNU Bash 4.4 2016 August 26 16

剩余77页未读，继续阅读

neffoor

粉丝: 0
资源: 2

GNU Bourne-Again Shell (bash 4.4) 用户手册

bashdb4.4适用于bash4.4版本以上

修复bash漏洞的bash-4.4.tar.gz源码包

学习 bash.pdf

Ubuntu16.04如何升级bash到4.4以上

vscode中终端bash-4.4# 这个无法显示到具体执行目录

-bash-4.4# free -h total used free shared buff/cache available Mem: 503Gi 409Gi 5.4Gi 654Mi 88Gi 90Gi Swap: 4.0Gi 4.0Gi 1.0Mi -bash-4.4#

bash-4.4$ ./startup.sh The JAVA_HOME environment variable is not defined correctly JAVA_HOME=/usr/local/jdk1.8 This environment variable is needed to run this program NB: JAVA_HOME should point to a JDK not a JRE bash-4.4$

bash-4.4# uname -r 3.10.0-693.21.1.el7.x86_64

linux8命令提示符变成bash-4..4

bash: tar-zxvf:

最新资源