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Linux 手册页字母索引

这个页面基于 man7.org 的字母索引页 做了站内整理。命令名和原始链接保持准确，说明、导航和分区提示改成中文，同时为了云端访问速度，默认只渲染当前字母分组。

索引条目
14971
字母分组
28
缓存时间
2026-04-22 10:30:54

手册分区说明

  • 1用户命令与常用可执行程序
  • 2系统调用接口
  • 3C 函数库与开发接口
  • 5文件格式、配置文件与约定
  • 7概览、约定、协议与杂项
  • 8系统管理命令

像 accept(2) 这样的写法，括号里的数字就是它所属的 man 分区。先看名字，再看分区，判断会更快。

使用方式

1. 先选字母

这页已经改成按字母查看，首屏不会再一次性加载全部条目，更适合云端访问。

2. 再看分区

同名条目可能出现在不同分区，例如普通命令、系统调用、POSIX 版本或库函数版本。

3. 需要原文就点进 man7

每个条目都保留了原始 man7 链接，适合继续阅读完整英文手册页。

4. 搜索只过滤当前分组

为了避免把整份索引都塞进页面里，当前搜索只在你打开的字母分组内即时过滤。

字母导航

点击字母切换分组。现在默认只渲染当前分组，访问速度会比整页全部展开稳定很多。

. 3 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
当前分组 U
当前条目 300
总条目 14971
数据来源 本地缓存

当前优先使用本地缓存以保证访问速度。缓存超过 24 小时也不会在访客请求时阻塞刷新。

U
共 300 条
回到字母导航
u32(8) 系统管理命令
universal 32bit traffic control filter
uabs(3) C 函数库
compute the absolute value of an integer
ualarm(3) C 函数库
schedule signal after given number of microseconds
uclampset(1) 用户命令
manipulate the utilization clamping attributes of the system or a process
ucmatose(1) 用户命令
RDMA CM connection and simple ping-pong test.
uconv(1) 用户命令
convert data from one encoding to another
udaddy(1) 用户命令
RDMA CM datagram setup and simple ping-pong test.
udev(7) 约定、概览与杂项
Dynamic device management
udev.conf(5) 文件格式与约定
Configuration for device event managing daemon
udev.conf.d(5) 文件格式与约定
Configuration for device event managing daemon
udevadm(8) 系统管理命令
udev management tool
udev_new(3) C 函数库
Create, acquire and release a udev context object
udev_ref(3) C 函数库
Create, acquire and release a udev context object
udev_unref(3) C 函数库
Create, acquire and release a udev context object
udfinfo(1) 用户命令
show information about UDF filesystem
udflabel(8) 系统管理命令
show or change UDF filesystem label
udp(7) 约定、概览与杂项
User Datagram Protocol for IPv4
udpdump(1) 用户命令
Provide a UDP receiver that gets packets from network devices (like Aruba routers) and exports them in PCAP format.
udplite(7) 约定、概览与杂项
Lightweight User Datagram Protocol
udpong(1) 用户命令
unreliable datagram streaming over RDMA ping-pong test.
UFFDIO_API(2const) 手册分区 2const
enable operation of the userfaultfd and perform API handshake
uffdio_api(2const) 手册分区 2const
enable operation of the userfaultfd and perform API handshake
UFFDIO_COPY(2const) 手册分区 2const
atomically copy a continuous memory chunk into the userfault registered range
uffdio_copy(2const) 手册分区 2const
atomically copy a continuous memory chunk into the userfault registered range
UFFDIO_MOVE(2const) 手册分区 2const
atomically move a continuous memory chunk into the userfault registered range
uffdio_move(2const) 手册分区 2const
atomically move a continuous memory chunk into the userfault registered range
uimaxabs(3) C 函数库
compute the absolute value of an integer
ukify(1) 用户命令
Combine components into a signed Unified Kernel Image for UEFI systems
ul(1) 用户命令
do underlining
ulabs(3) C 函数库
compute the absolute value of an integer
ulckpwdf(3) C 函数库
get shadow password file entry
ulimit(1p) POSIX 用户命令
set or report file size limit
ulimit(3) C 函数库
get and set user limits
ulimit(3p) POSIX 函数库
get and set process limits
ullabs(3) C 函数库
compute the absolute value of an integer
umad_class_str(3) C 函数库
class of functions to return string representations of enums
umad_done(3) C 函数库
perform library initialization and finalization
umad_get_ca(3) C 函数库
get and release InfiniBand device port attributes
umad_init(3) C 函数库
perform library initialization and finalization
umad_register(3) C 函数库
register the specified management class and version for port
umad_register2(3) C 函数库
register the specified management class and version for port
umad_set_addr(3) C 函数库
set MAD address fields within umad buffer using host ordering
umad_set_grh(3) C 函数库
set GRH fields within umad buffer using host ordering
umask(1p) POSIX 用户命令
get or set the file mode creation mask
umask(2) 系统调用
set file mode creation mask
umask(3p) POSIX 函数库
set and get the file mode creation mask
umaxabs(3) C 函数库
compute the absolute value of an integer
umount(8) 系统管理命令
unmount filesystems
unalias(1p) POSIX 用户命令
remove alias definitions
uname(1) 用户命令
print system information
uname(1p) POSIX 用户命令
return system name
uname(2) 系统调用
get name and information about current kernel
uname(3p) POSIX 函数库
get the name of the current system
uname26(8) 系统管理命令
change reported architecture in new program environment and/or set personality flags
unctrl(3x) 扩展函数 / curses
miscellaneous curses utility routines
unget(1p) POSIX 用户命令
undo a previous get of an SCCS file (DEVELOPMENT)
ungetc(3) C 函数库
input of characters and strings
ungetc(3p) POSIX 函数库
push byte back into input stream
ungetch(3x) 扩展函数 / curses
get (or push back) characters from curses terminal keyboard buffer
ungetwc(3) C 函数库
push back a wide character onto a FILE stream
ungetwc(3p) POSIX 函数库
character code back into the input stream
unget_wch(3x) 扩展函数 / curses
get (or push back) a wide character from curses terminal keyboard buffer
unicode(7) 约定、概览与杂项
universal character set
unicode_stop(1) 用户命令
revert keyboard and console from unicode mode
unimplemented(2) 系统调用
未实现的系统调用
原文：unimplemented system calls
uniq(1) 用户命令
report or omit repeated lines
uniq(1p) POSIX 用户命令
report or filter out repeated lines in a file
unistd.h(0p) POSIX 头文件
standard symbolic constants and types
units(7) 约定、概览与杂项
decimal and binary prefixes
unix(7) 约定、概览与杂项
sockets for local interprocess communication
unix_chkpwd(8) 系统管理命令
Helper binary that verifies the password of the current user
unix_update(8) 系统管理命令
Helper binary that updates the password of a given user
unlink(1) 用户命令
call the unlink function to remove the specified file
unlink(1p) POSIX 用户命令
call the unlink() function
unlink(2) 系统调用
delete a name and possibly the file it refers to
unlink(3p) POSIX 函数库
remove a directory entry
unlinkat(2) 系统调用
delete a name and possibly the file it refers to
unlockpt(3) C 函数库
unlock a pseudoterminal master/slave pair
unpost_form(3x) 扩展函数 / curses
write or erase forms from associated subwindows
unpost_menu(3x) 扩展函数 / curses
write or erase menus from associated subwindows
unset(1p) POSIX 用户命令
unset values and attributes of variables and functions
unsetenv(3) C 函数库
change or add an environment variable
unsetenv(3p) POSIX 函数库
remove an environment variable
unsetfiles(1) 用户命令
Remove SELinux file security contexts.
unshare(1) 用户命令
run program in new namespaces
unshare(2) 系统调用
disassociate parts of the process execution context
untouchwin(3x) 扩展函数 / curses
control terminal output refresh in a curses window
UP(3x) 扩展函数 / curses
curses emulation of termcap
updatectl(1) 用户命令
Control the system update service
updwtmp(3) C 函数库
append an entry to the wtmp file
updwtmpx(3) C 函数库
append an entry to the wtmp file
uptime(1) 用户命令
Tell how long the system has been running.
urandom(4) 设备与特殊文件
kernel random number source devices
uri(7) 约定、概览与杂项
uniform resource identifier (URI), including a URL or URN
url(7) 约定、概览与杂项
uniform resource identifier (URI), including a URL or URN
urn(7) 约定、概览与杂项
uniform resource identifier (URI), including a URL or URN
usbhid-dump(8) 系统管理命令
dump USB HID device report descriptors and streams
usbreset(1) 用户命令
send a USB port reset to a USB device
use_env(3x) 扩展函数 / curses
miscellaneous curses utility routines
uselocale(3) C 函数库
set/get the locale for the calling thread
user.conf.d(5) 文件格式与约定
System and session service manager configuration files
user.service(5) 文件格式与约定
System units to start the user manager
useradd(8) 系统管理命令
create a new user or update default new user information
user_caps(5) 文件格式与约定
user-defined terminfo capability format
user_contexts(5) 文件格式与约定
The SELinux user contexts configuration files
userdbctl(1) 用户命令
Inspect users, groups and group memberships
userdel(8) 系统管理命令
delete a user account and related files
userfaultfd(2) 系统调用
create a file descriptor for handling page faults in user space
usermod(8) 系统管理命令
modify a user account
users(1) 用户命令
print the user names of users currently logged in to the current host
use_screen(3x) 扩展函数 / curses
curses support for multi-threaded applications
use_tioctl(3x) 扩展函数 / curses
miscellaneous curses utility routines
use_window(3x) 扩展函数 / curses
curses support for multi-threaded applications
usleep(3) C 函数库
suspend execution for microsecond intervals
ustat(2) 系统调用
get filesystem statistics
UTF-8(7) 约定、概览与杂项
an ASCII compatible multibyte Unicode encoding
utf-8(7) 约定、概览与杂项
an ASCII compatible multibyte Unicode encoding
utf8(7) 约定、概览与杂项
an ASCII compatible multibyte Unicode encoding
utime(2) 系统调用
change file last access and modification times
utime(3p) POSIX 函数库
set file access and modification times
utime.h(0p) POSIX 头文件
access and modification times structure
utimensat(2) 系统调用
change file timestamps with nanosecond precision
utimensat(3p) POSIX 函数库
set file access and modification times
utimes(2) 系统调用
change file last access and modification times
utimes(3p) POSIX 函数库
set file access and modification times
utmp(5) 文件格式与约定
login records
utmpdump(1) 用户命令
dump UTMP and WTMP files in raw format
utmpx(5) 文件格式与约定
login records
utmpx.h(0p) POSIX 头文件
user accounting database definitions
uucp(1p) POSIX 用户命令
to-system copy
uuid(3) C 函数库
DCE compatible Universally Unique Identifier library
uuid_clear(3) C 函数库
reset value of UUID variable to the NULL value
uuidd(8) 系统管理命令
UUID generation daemon
uuid_is_null(3) C 函数库
compare the value of the UUID to the NULL value
uuidparse(1) 用户命令
a utility to parse unique identifiers
uuid_parse(3) C 函数库
convert an input UUID string into binary representation
uuid_time(3) C 函数库
extract the time at which the UUID was created
uuid_unparse(3) C 函数库
convert a UUID from binary representation to a string
uustat(1p) POSIX 用户命令
uucp status enquiry and job control
uux(1p) POSIX 用户命令
remote command execution