永久更改 Kali Linux 中“date”命令的输出格式

Question 1

您可以知道date它应该如何格式化其输出：

%%   a literal %
  %a   locale's abbreviated weekday name (e.g., Sun)
  %A   locale's full weekday name (e.g., Sunday)
  %b   locale's abbreviated month name (e.g., Jan)
  %B   locale's full month name (e.g., January)
  %c   locale's date and time (e.g., Thu Mar  3 23:05:25 2005)
  %C   century; like %Y, except omit last two digits (e.g., 20)
  %d   day of month (e.g., 01)
  %D   date; same as %m/%d/%y
  %e   day of month, space padded; same as %_d
  %F   full date; like %+4Y-%m-%d
  %g   last two digits of year of ISO week number (see %G)
  %G   year of ISO week number (see %V); normally useful only with %V
  %h   same as %b
  %H   hour (00..23)
  %I   hour (01..12)
  %j   day of year (001..366)
  %k   hour, space padded ( 0..23); same as %_H
  %l   hour, space padded ( 1..12); same as %_I
  %m   month (01..12)
  %M   minute (00..59)
  %n   a newline
  %N   nanoseconds (000000000..999999999)
  %p   locale's equivalent of either AM or PM; blank if not known
  %P   like %p, but lower case
  %q   quarter of year (1..4)
  %r   locale's 12-hour clock time (e.g., 11:11:04 PM)
  %R   24-hour hour and minute; same as %H:%M
  %s   seconds since the Epoch (1970-01-01 00:00 UTC)
  %S   second (00..60)
  %t   a tab
  %T   time; same as %H:%M:%S
  %u   day of week (1..7); 1 is Monday
  %U   week number of year, with Sunday as first day of week (00..53)
  %V   ISO week number, with Monday as first day of week (01..53)
  %w   day of week (0..6); 0 is Sunday
  %W   week number of year, with Monday as first day of week (00..53)
  %x   locale's date representation (e.g., 12/31/99)
  %X   locale's time representation (e.g., 23:13:48)
  %y   last two digits of year (00..99)
  %Y   year
  %z   +hhmm numeric time zone (e.g., -0400)
  %:z  +hh:mm numeric time zone (e.g., -04:00)
  %::z  +hh:mm:ss numeric time zone (e.g., -04:00:00)
  %:::z  numeric time zone with : to necessary precision (e.g., -04, +05:30)
  %Z   alphabetic time zone abbreviation (e.g., EDT)

在您的情况下，命令如下：

date +"%a %d %b %Y %r %Z"

通过设置别名，您可以更改date命令的行为：

alias date='date +"%a %d %b %Y %r %Z"'

您可以将别名放入您的帐户中，~/.bashrc以使当前用户的更改永久生效。

Answer

您可以知道date它应该如何格式化其输出：

%%   a literal %
  %a   locale's abbreviated weekday name (e.g., Sun)
  %A   locale's full weekday name (e.g., Sunday)
  %b   locale's abbreviated month name (e.g., Jan)
  %B   locale's full month name (e.g., January)
  %c   locale's date and time (e.g., Thu Mar  3 23:05:25 2005)
  %C   century; like %Y, except omit last two digits (e.g., 20)
  %d   day of month (e.g., 01)
  %D   date; same as %m/%d/%y
  %e   day of month, space padded; same as %_d
  %F   full date; like %+4Y-%m-%d
  %g   last two digits of year of ISO week number (see %G)
  %G   year of ISO week number (see %V); normally useful only with %V
  %h   same as %b
  %H   hour (00..23)
  %I   hour (01..12)
  %j   day of year (001..366)
  %k   hour, space padded ( 0..23); same as %_H
  %l   hour, space padded ( 1..12); same as %_I
  %m   month (01..12)
  %M   minute (00..59)
  %n   a newline
  %N   nanoseconds (000000000..999999999)
  %p   locale's equivalent of either AM or PM; blank if not known
  %P   like %p, but lower case
  %q   quarter of year (1..4)
  %r   locale's 12-hour clock time (e.g., 11:11:04 PM)
  %R   24-hour hour and minute; same as %H:%M
  %s   seconds since the Epoch (1970-01-01 00:00 UTC)
  %S   second (00..60)
  %t   a tab
  %T   time; same as %H:%M:%S
  %u   day of week (1..7); 1 is Monday
  %U   week number of year, with Sunday as first day of week (00..53)
  %V   ISO week number, with Monday as first day of week (01..53)
  %w   day of week (0..6); 0 is Sunday
  %W   week number of year, with Monday as first day of week (00..53)
  %x   locale's date representation (e.g., 12/31/99)
  %X   locale's time representation (e.g., 23:13:48)
  %y   last two digits of year (00..99)
  %Y   year
  %z   +hhmm numeric time zone (e.g., -0400)
  %:z  +hh:mm numeric time zone (e.g., -04:00)
  %::z  +hh:mm:ss numeric time zone (e.g., -04:00:00)
  %:::z  numeric time zone with : to necessary precision (e.g., -04, +05:30)
  %Z   alphabetic time zone abbreviation (e.g., EDT)

在您的情况下，命令如下：

date +"%a %d %b %Y %r %Z"

通过设置别名，您可以更改date命令的行为：

alias date='date +"%a %d %b %Y %r %Z"'

您可以将别名放入您的帐户中，~/.bashrc以使当前用户的更改永久生效。

Question 2

命令的默认格式date(1)深埋在语言环境系统中（具体来说，是date_fmt中的设置LC_TIME）。 Locale 是用于指定与位置相关的内容的系统，例如一周中的哪一天首先出现、纸张大小、电话号码格式、是 d/m/y 还是 m/d/y 以及每个数字的位数等。

2018 年 Ubuntu 18.04LTS 发布后，（美国英语）用户的默认设置date(1)发生了变化。en_US在美国，date(1)在高于 18.04 的 Ubuntu 版本中，该命令生成的日期采用 12 小时制，其中包含 AM 或 PM。我不知道其他发行版做了什么或什么时候做的。

C/POSIX 语言环境是一种与位置无关的语言环境，保证永远不会更改。这几乎就是 Unix 系统在开始调整语言环境之前所做的事情。它的语言环境称为 C。

根据您的情况，您有多种选择：

如果您没有依赖于使用该date(1)命令的旧数据的软件，您可以考虑继续使用它。事实上，在美国，人们使用 12 小时制和 AM/PM。
如果像我一样，您想继续date(1)在脚本中使用以特定格式生成日期，则可以在命令行中使用格式说明符：
```
$ date +"%a %b %e %H:%M:%S %Z %Y"
Mon Jun 12 15:30:44 EDT 2023
```
您还可以指定与环境变量一起使用的区域设置LANG，并将其设置为 C:
```
$ LANG=C date
Mon Jun 12 15:30:44 EDT 2023
```
可以为给定的 shell 设置
```
$ export LANG=C
$ date
Mon Jun 12 15:30:44 EDT 2023
```
如果您希望每个 shell 都使用它，请将export LANG=C行放入~/.bash_aliases.

如果您想要date(1)生成不带参数的给定格式，即使是由其他用户调用或不是从 shell 调用，那么您需要更改该date(1)命令的系统默认格式。这涉及更多一点：

# Modify one line in the en_US locale file:
cd /usr/share/i18n/locales
sed -e '/date_fmt/ s/%r/%H:%M:%S/'  en_US > en_US@Cdate

# List it as a supported locale:
cat >> /etc/locale.gen << EOF
[email protected] UTF-8
EOF

# compile the locale database
locale-gen

# select the new locale (modifies /etc/default/locale)
update-locale [email protected]

这对新登录生效。

Answer