phatez@phatez-laptop:~$ help
GNU bash, version 4.3.46(1)-release (x86_64-pc-linux-gnu)
These shell commands are defined internally. Type `help' to see this list.
Type `help name' to find out more about the function `name'.
Use `info bash' to find out more about the shell in general.
Use `man -k' or `info' to find out more about commands not in this list.
A star (*) next to a name means that the command is disabled.
job_spec [&] history [-c] [-d offset] [n] or history -anrw [filena>
(( expression )) if COMMANDS; then COMMANDS; [ elif COMMANDS; then COM>
. filename [arguments] jobs [-lnprs] [jobspec ...] or jobs -x command [args]>
: kill [-s sigspec | -n signum | -sigspec] pid | jobspe>
[ arg... ] let arg [arg ...]
[[ expression ]] local [option] name[=value] ...
alias [-p] [name[=value] ... ] logout [n]
bg [job_spec ...] mapfile [-n count] [-O origin] [-s count] [-t] [-u fd>
bind [-lpsvPSVX] [-m keymap] [-f filename] [-q name] [> popd [-n] [+N | -N]
break [n] printf [-v var] format [arguments]
builtin [shell-builtin [arg ...]] pushd [-n] [+N | -N | dir]
caller [expr] pwd [-LP]
case WORD in [PATTERN [| PATTERN]...) COMMANDS ;;]... > read [-ers] [-a array] [-d delim] [-i text] [-n nchar>
cd [-L|[-P [-e]] [-@]] [dir] readarray [-n count] [-O origin] [-s count] [-t] [-u >
command [-pVv] command [arg ...] readonly [-aAf] [name[=value] ...] or readonly -p
compgen [-abcdefgjksuv] [-o option] [-A action] [-G g> return [n]
complete [-abcdefgjksuv] [-pr] [-DE] [-o option] [-A a> select NAME [in WORDS ... ;] do COMMANDS; done
compopt [-o|+o option] [-DE] [name ...] set [-abefhkmnptuvxBCHP] [-o option-name] [--] [arg .>
continue [n] shift [n]
coproc [NAME] command [redirections] shopt [-pqsu] [-o] [optname ...]
declare [-aAfFgilnrtux] [-p] [name[=value] ...] source filename [arguments]
dirs [-clpv] [+N] [-N] suspend [-f]
disown [-h] [-ar] [jobspec ...] test [expr]
echo [-neE] [arg ...] time [-p] pipeline
enable [-a] [-dnps] [-f filename] [name ...] times
eval [arg ...] trap [-lp] [[arg] signal_spec ...]
exec [-cl] [-a name] [command [arguments ...]] [redire> true
exit [n] type [-afptP] name [name ...]
export [-fn] [name[=value] ...] or export -p typeset [-aAfFgilrtux] [-p] name[=value] ...
false ulimit [-SHabcdefilmnpqrstuvxT] [limit]
fc [-e ename] [-lnr] [first] [last] or fc -s [pat=rep]> umask [-p] [-S] [mode]
fg [job_spec] unalias [-a] name [name ...]
for NAME [in WORDS ... ] ; do COMMANDS; done unset [-f] [-v] [-n] [name ...]
for (( exp1; exp2; exp3 )); do COMMANDS; done until COMMANDS; do COMMANDS; done
function name { COMMANDS ; } or name () { COMMANDS ; }> variables - Names and meanings of some shell variable>
getopts optstring name [arg] wait [-n] [id ...]
hash [-lr] [-p pathname] [-dt] [name ...] while COMMANDS; do COMMANDS; done
help [-dms] [pattern ...] { COMMANDS ; }
phatez@phatez-laptop:~$ man ulimit
phatez@phatez-laptop:~$ man disown
No manual entry for disown
phatez@phatez-laptop:~$
答案1
disown是内置的 bash。因此man bash将显示...
放弃 [-ar] [-h] [jobspec ...]
不使用选项，从活动作业表中删除每个作业规范。如果不存在作业规范，并且未提供 -a 或 -r 选项，则使用当前作业。如果给出了 -h 选项，则不会从表中删除每个作业规范，但会对其进行标记，以便在 shell 收到 SIGHUP 时不会向作业发送 SIGHUP。如果没有提供作业规范，则 -a 选项表示删除或标记所有作业；不带作业规范参数的 -r 选项将操作限制为正在运行的作业。除非作业规范未指定有效作业，否则返回值为 0。
这样的例子还有很多。以下是列表。
列出帮助类型
help disown
或者其他 ubuntu 命令？
所有 Ubuntu（更准确地说是 Linux）命令都有手册页。
ulimit确实有手册页。
ULIMIT(3) Linux 程序员手册 ULIMIT(3)
名称 ulimit - 获取和设置用户限制
概要
#include <ulimit.h> long ulimit(int cmd, long newlimit);
但你可能的意思是范围？
2种方式：
$help ulimit
ulimit: ulimit [-SHabcdefilmnpqrstuvxT] [limit]
Modify shell resource limits.
Provides control over the resources available to the shell and processes
it creates, on systems that allow such control.
Options:
-S use the `soft' resource limit
-H use the `hard' resource limit
-a all current limits are reported
-b the socket buffer size
-c the maximum size of core files created
...
$ ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 46690
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 46690
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
答案2
键入时，help您会看到 bash 内置的命令。要查看这些命令的帮助，请键入help <command>：
help ulimit
help disown
当您使用man（manual 的缩写）时，您将显示不属于 bash 的二进制程序的帮助。您会注意到，ulimit如果您键入 ，您将获得 的帮助man ulimit。但是，ulimit 的手册不是 bash 命令的手册。当您键入 时，man ulimit您将获得 C 编程头文件的手册ulimit.h，这是完全不同的东西。
答案3
ulimit和disown是 Bash 内置函数，它们没有自己的手册页，但在 Bash 手册页中有描述。
如果您正在运行 bash，则可以使用以下help命令，例如：
$ help disown
您可能希望将输出导入，less以便可以滚动和搜索，例如
$ help disown | less
答案4
当不确定某个命令是 Bash 内置命令、可执行文件、两者还是其他什么时：
$ type -a kill
kill is aliased to `echo 'You should not use kill - use OUPMclient -K instead.';'
kill is a shell builtin
kill is /usr/bin/kill
kill is /bin/kill
这是一个特殊的例子，因为我们的提供商希望我们使用其他命令而不是kill他们的应用程序的流程。