$ su -
パスワード:tokyoec
#

# find / -name hosts
/etc/hosts
/etc/avahi/hosts

# find /var/log -name messages
/var/log/messages

# cd /
# find ./var/log -name messages
./var/log/messages

# exit
$

$ cal --help
使い方:
cal [オプション] [[[日] 月] 年]
cal [options] 
 
カレンダーまたはその一部を表示します。
引数を付けない場合は今月を表示します。
 
オプション:
-1, --one             1 か月分だけを表示します (既定値)
-3, --three           3 か月分の日付を表示します
-n, --months     show num months starting with date's month
-S, --span            span the date when displaying multiple months
-s, --sunday          週の開始を日曜日にします
-m, --monday          週の開始を月曜日にします
-j, --julian          use day-of-year for all calendars
    --reform     Gregorian reform date (1752|gregorian|iso|julian)
    --iso             --reform=iso と同じ
-y, --year            年全体を表示します
-Y, --twelve          show the next twelve months
-w, --week[=]    US または ISO-8601 形式の週番号を表示
    --color[=<時期>]  メッセージを色づけします
                          (auto、always、never のどれか)
                          カラー表示はデフォルトで有効です
 
-h, --help            このヘルプを表示します
-V, --version         バージョンを表示します
 
詳しくは cal(1) をお読みください。

$ man cal
  CAL(1)                                                                User Commands                                                                CAL(1)

  NAME
         cal - display a calendar
  
  SYNOPSIS
         cal [options] [[[day] month] year]
         cal [options] [timestamp|monthname]
  
  DESCRIPTION
         cal displays a simple calendar.  If no arguments are specified, the current month is displayed.
  
         The month may be specified as a number (1-12), as a month name or as an abbreviated month name according to the current locales.
  
         Two different calendar systems are used, Gregorian and Julian.  These are nearly identical systems with Gregorian making a small adjustment to the
         frequency of leap years; this facilitates improved synchronization with solar events like the equinoxes.  The Gregorian calendar reform was intro‐
         duced in 1582, but its adoption continued up to 1923.  By default cal uses the adoption date of 3 Sept 1752.  From that date forward the Gregorian
         calendar is displayed; previous dates use the Julian calendar system.  11 days were removed at the time of adoption to bring the calendar in  sync
         with  solar  events.   So Sept 1752 has a mix of Julian and Gregorian dates by which the 2nd is followed by the 14th (the 3rd through the 13th are
         absent).
  
         Optionally, either the proleptic Gregorian calendar or the Julian calendar may be used exclusively.  See --reform below.
  
  OPTIONS
         -1, --one
                Display single month output.  (This is the default.)
  
         -3, --three
                Display three months spanning the date.
  
         -n , --months number
                Display number of months, starting from the month containing the date.
  
         -S, --span
                Display months spanning the date.
  
         -s, --sunday
                Display Sunday as the first day of the week.
  
         -m, --monday
                Display Monday as the first day of the week.
  
         --iso  Display the proleptic Gregorian calendar exclusively.  See --reform below.
  
         -j, --julian
                Use day-of-year numbering for all calendars.  These are also called ordinal days.  Ordinal days range from 1 to 366.  This option does  not
                switch from the Gregorian to the Julian calendar system, that is controlled by the --reform option.
  
                Sometimes  Gregorian calendars using ordinal dates are referred to as Julian calendars.  This can be confusing due to the many date related
                conventions that use Julian in their name: (ordinal) julian date, julian (calendar) date, (astronomical)  julian  date,  (modified)  julian
                date,  and more.  This option is named julian, because ordinal days are identified as julian by the POSIX standard.  However, be aware that
                cal also uses the Julian calendar system.  See DESCRIPTION above.
  
         --reform val
                This option sets the adoption date of the Gregorian calendar reform.  Calendar dates previous to reform use  the  Julian  calendar  system.
                Calendar dates after reform use the Gregorian calendar system.  The argument val can be:
  
                ・ 1752 - sets 3 September 1752 as the reform date (default).  This is when the Gregorian calendar reform was adopted by the British Empire.
  
                ・ gregorian  - display Gregorian calendars exclusively.  This special placeholder sets the reform date below the smallest year that cal can
                  use; meaning all calendar output uses the Gregorian calendar system.  This is called the  proleptic  Gregorian  calendar,  because  dates
                  prior to the calendar system's creation use extrapolated values.
  
                ・ iso  - alias of gregorian.  The ISO 8601 standard for the representation of dates and times in information interchange requires using the
                  proleptic Gregorian calendar.
  
                ・ julian - display Julian calendars exclusively.  This special placeholder sets the reform date above the largest year that  cal  can  use;
                  meaning all calendar output uses the Julian calendar system.
  
                See DESCRIPTION above.
  
         -y, --year
                Display a calendar for the whole year.
  
         -Y, --twelve
                Display a calendar for the next twelve months.
  
         -w, --week[=number]
                Display week numbers in the calendar (US or ISO-8601).
  
         --color[=when]
                Colorize  the output.  The optional argument when can be auto, never or always.  If the when argument is omitted, it defaults to auto.  The
                colors can be disabled; for the current built-in default see the --help output.  See also the COLORS section.
  
         -V, --version
                Display version information and exit.
  
         -h, --help
                Display help text and exit.
  
  PARAMETERS
         Single digits-only parameter (e.g. 'cal 2020')
                Specifies the year to be displayed; note the year must be fully specified: cal 89 will not display a calendar for 1989.
  
         Single string parameter (e.g. 'cal tomorrow' or 'cal August')
                Specifies timestamp or a month name (or abbreviated name) according to the current locales.
  
                The special placeholders are accepted when parsing timestamp, "now" may be used to refer to the current time, "today", "yesterday", "tomor‐
                row" refer to of the current day, the day before or the next day, respectively.
  
                The  relative date specifications are also accepted, in this case "+" is evaluated to the current time plus the specified time span. Corre‐
                spondingly, a time span that is prefixed with "-" is evaluated to the current time minus the specified time  span,  for  example  '+2days'.
                Instead  of prefixing the time span with "+" or "-", it may also be suffixed with a space and the word "left" or "ago" (for example '1 week
                ago').
  CAL(1)                                                                User Commands                                                                CAL(1)
  
  NAME
         cal - display a calendar
  
  SYNOPSIS
         cal [options] [[[day] month] year]
         cal [options] [timestamp|monthname]
  
  DESCRIPTION
         cal displays a simple calendar.  If no arguments are specified, the current month is displayed.
  
         The month may be specified as a number (1-12), as a month name or as an abbreviated month name according to the current locales.
  
         Two different calendar systems are used, Gregorian and Julian.  These are nearly identical systems with Gregorian making a small adjustment to the
         frequency of leap years; this facilitates improved synchronization with solar events like the equinoxes.  The Gregorian calendar reform was intro‐
         duced in 1582, but its adoption continued up to 1923.  By default cal uses the adoption date of 3 Sept 1752.  From that date forward the Gregorian
         calendar is displayed; previous dates use the Julian calendar system.  11 days were removed at the time of adoption to bring the calendar in  sync
         with  solar  events.   So Sept 1752 has a mix of Julian and Gregorian dates by which the 2nd is followed by the 14th (the 3rd through the 13th are
         absent).
  
         Optionally, either the proleptic Gregorian calendar or the Julian calendar may be used exclusively.  See --reform below.
  
  OPTIONS
         -1, --one
                Display single month output.  (This is the default.)
  
         -3, --three
                Display three months spanning the date.
  
         -n , --months number
                Display number of months, starting from the month containing the date.
  
         -S, --span
                Display months spanning the date.
  
         -s, --sunday
                Display Sunday as the first day of the week.
  
         -m, --monday
                Display Monday as the first day of the week.
  
         --iso  Display the proleptic Gregorian calendar exclusively.  See --reform below.
  
         -j, --julian
                Use day-of-year numbering for all calendars.  These are also called ordinal days.  Ordinal days range from 1 to 366.  This option does  not
                switch from the Gregorian to the Julian calendar system, that is controlled by the --reform option.
  
                Sometimes  Gregorian calendars using ordinal dates are referred to as Julian calendars.  This can be confusing due to the many date related
                conventions that use Julian in their name: (ordinal) julian date, julian (calendar) date, (astronomical)  julian  date,  (modified)  julian
                date,  and more.  This option is named julian, because ordinal days are identified as julian by the POSIX standard.  However, be aware that
                cal also uses the Julian calendar system.  See DESCRIPTION above.
  
         --reform val
                This option sets the adoption date of the Gregorian calendar reform.  Calendar dates previous to reform use  the  Julian  calendar  system.
                Calendar dates after reform use the Gregorian calendar system.  The argument val can be:
  
                ・ 1752 - sets 3 September 1752 as the reform date (default).  This is when the Gregorian calendar reform was adopted by the British Empire.
  
                ・ gregorian  - display Gregorian calendars exclusively.  This special placeholder sets the reform date below the smallest year that cal can
                  use; meaning all calendar output uses the Gregorian calendar system.  This is called the  proleptic  Gregorian  calendar,  because  dates
                  prior to the calendar system's creation use extrapolated values.
  
                ・ iso  - alias of gregorian.  The ISO 8601 standard for the representation of dates and times in information interchange requires using the
                  proleptic Gregorian calendar.
  
                ・ julian - display Julian calendars exclusively.  This special placeholder sets the reform date above the largest year that  cal  can  use;
                  meaning all calendar output uses the Julian calendar system.
  
                See DESCRIPTION above.
  
         -y, --year
                Display a calendar for the whole year.
  
         -Y, --twelve
                Display a calendar for the next twelve months.
  
         -w, --week[=number]
                Display week numbers in the calendar (US or ISO-8601).
  
         --color[=when]
                Colorize  the output.  The optional argument when can be auto, never or always.  If the when argument is omitted, it defaults to auto.  The
                colors can be disabled; for the current built-in default see the --help output.  See also the COLORS section.
  
         -V, --version
                Display version information and exit.
  
         -h, --help
                Display help text and exit.
  
  PARAMETERS
         Single digits-only parameter (e.g. 'cal 2020')
                Specifies the year to be displayed; note the year must be fully specified: cal 89 will not display a calendar for 1989.
  
         Single string parameter (e.g. 'cal tomorrow' or 'cal August')
                Specifies timestamp or a month name (or abbreviated name) according to the current locales.
  
                The special placeholders are accepted when parsing timestamp, "now" may be used to refer to the current time, "today", "yesterday", "tomor‐
                row" refer to of the current day, the day before or the next day, respectively.
  
                The  relative date specifications are also accepted, in this case "+" is evaluated to the current time plus the specified time span. Corre‐
                spondingly, a time span that is prefixed with "-" is evaluated to the current time minus the specified time  span,  for  example  '+2days'.
                Instead  of prefixing the time span with "+" or "-", it may also be suffixed with a space and the word "left" or "ago" (for example '1 week
                ago').
  
         Two parameters (e.g. 'cal 11 2020')
                Denote the month (1 - 12) and year.
  
         Three parameters (e.g. 'cal 25 11 2020')
                Denote the day (1-31), month and year, and the day will be highlighted if the calendar is displayed on a terminal.  If  no  parameters  are
                specified, the current month's calendar is displayed.
  
  NOTES
         A year starts on January 1.  The first day of the week is determined by the locale or the --sunday and --monday options.
  
         The week numbering depends on the choice of the first day of the week.  If it is Sunday then the customary North American numbering is used, where
         1 January is in week number 1.  If it is Monday then the ISO 8601 standard week numbering is used, where the first Thursday is in week number 1.
  
  COLORS
         Implicit coloring can be disabled as follows:
  
                touch /etc/terminal-colors.d/cal.disable
  
         See terminal-colors.d(5) for more details about colorization configuration.
  
  BUGS
         The default cal output uses 3 September 1752 as the Gregorian calendar reform date.  The historical reform  dates for the other locales, including
         its introduction in October 1582, are not implemented.
  
         Alternative calendars, such as the Umm al-Qura, the Solar Hijri, the Ge'ez, or the lunisolar Hindu, are not supported.
  
  HISTORY
         A cal command appeared in Version 6 AT&T UNIX.
  
  AVAILABILITY
         The cal command is part of the util-linux package and is available from https://www.kernel.org/pub/linux/utils/util-linux/.
  
  util-linux                                                             January 2018                                                                CAL(1)

$ which pwd
/usr/bin/pwd

$ ls /usr/bin/pwd
/usr/bin/pwd