Arithmétique des dates dans les scripts shell Unix

j'ai écrit un script bash pour convertir les dates exprimées en anglais en conventionnel mm/jj/aaaa dates. Il est appelé ComputeDate.

Voici quelques exemples de son utilisation. Par souci de concision, j'ai placé la sortie de chaque invocation sur la même ligne que l'invocation, séparée par un côlon (:). Les citations ci-dessous sont des nécessaire lors de l'exécution ComputeDate:

$ ComputeDate 'yesterday': 03/19/2010
$ ComputeDate 'yes': 03/19/2010
$ ComputeDate 'today': 03/20/2010
$ ComputeDate 'tod': 03/20/2010
$ ComputeDate 'now': 03/20/2010
$ ComputeDate 'tomorrow': 03/21/2010
$ ComputeDate 'tom': 03/21/2010
$ ComputeDate '10/29/32': 10/29/2032
$ ComputeDate 'October 29': 10/1/2029
$ ComputeDate 'October 29, 2010': 10/29/2010
$ ComputeDate 'this monday': 'this monday' has passed.  Did you mean 'next monday?'
$ ComputeDate 'a week after today': 03/27/2010
$ ComputeDate 'this satu': 03/20/2010
$ ComputeDate 'next monday': 03/22/2010
$ ComputeDate 'next thur': 03/25/2010
$ ComputeDate 'mon in 2 weeks': 03/28/2010
$ ComputeDate 'the last day of the month': 03/31/2010
$ ComputeDate 'the last day of feb': 2/28/2010
$ ComputeDate 'the last day of feb 2000': 2/29/2000
$ ComputeDate '1 week from yesterday': 03/26/2010
$ ComputeDate '1 week from today': 03/27/2010
$ ComputeDate '1 week from tomorrow': 03/28/2010
$ ComputeDate '2 weeks from yesterday': 4/2/2010
$ ComputeDate '2 weeks from today': 4/3/2010
$ ComputeDate '2 weeks from tomorrow': 4/4/2010
$ ComputeDate '1 week after the last day of march': 4/7/2010
$ ComputeDate '1 week after next Thursday': 4/1/2010
$ ComputeDate '2 weeks after the last day of march': 4/14/2010
$ ComputeDate '2 weeks after 1 day after the last day of march': 4/15/2010
$ ComputeDate '1 day after the last day of march': 4/1/2010
$ ComputeDate '1 day after 1 day after 1 day after 1 day after today': 03/24/2010

j'ai inclus ce script comme un réponse à ce problème parce qu'il illustre comment pour faire des opérations arithmétiques via un ensemble de fonctions bash et ces fonctions peuvent s'avérer utiles pour les autres. Il gère les années bissextiles et les siècles bissextiles correctement:

#! /bin/bash
#  ConvertDate -- convert a human-readable date to a MM/DD/YY date
#
#  Date ::= Month/Day/Year
#        |  Month/Day
#        |  DayOfWeek
#        |  [this|next] DayOfWeek
#        |  DayofWeek [of|in] [Number|next] weeks[s]
#        |  Number [day|week][s] from Date
#        |  the last day of the month
#        |  the last day of Month
#
#  Month ::= January | February | March | April | May | ...  | December
#  January  ::= jan | january | 1
#  February  ::= feb | january | 2
#  ...
#  December ::=  dec | december | 12
#  Day   ::= 1 | 2 | ... | 31
#  DayOfWeek ::= today | Sunday | Monday | Tuesday | ...  | Saturday
#  Sunday    ::= sun*
#  ...
#  Saturday  ::= sat*
#
#  Number ::= Day | a
#
#  Author: Larry Morell

if [ $# = 0 ]; then
   printdirections 
   exit
fi



# Request the value of a variable
GetVar () {
   Var=
   echo -n "$Var= [${!Var}]: "
   local X
   read X
   if [ ! -z $X ]; then
      eval $Var="$X"
   fi
}

IsLeapYear () {
   local Year=
   if [ $[20$Year % 4]  -eq  0 ]; then
      echo yes
   else
      echo no
   fi
}

# AddToDate -- compute another date within the same year

DayNames=(mon tue wed thu fri sat sun )  # To correspond with 'date' output

Day2Int () {
   ErrorFlag=
   case  in
      -e )
         ErrorFlag=-e; shift
         ;;
   esac
   local dow=
   n=0
   while  [ $n -lt 7 -a $dow != "${DayNames[n]}" ]; do
      let n++
   done
   if [ -z "$ErrorFlag" -a $n -eq 7 ]; then
      echo Cannot convert $dow to a numeric day of wee
      exit
   fi
   echo $[n+1]

}

Months=(31 28 31 30 31 30 31 31 30 31 30 31)
MonthNames=(jan feb mar apr may jun jul aug sep oct nov dec)
# Returns the month (1-12) from a date, or a month name
Month2Int () {
   ErrorFlag=
   case  in
      -e )
         ErrorFlag=-e; shift
         ;;
   esac
   M=
   Month=${M%%/*}  # Remove /...
   case $Month in
      [a-z]* )
         Month=${Month:0:3}
         M=0
         while [ $M -lt 12 -a ${MonthNames[M]} != $Month ]; do
            let M++
         done
         let M++
   esac
   if [  -z "$ErrorFlag" -a $M -gt 12 ]; then
      echo "'$Month' Is not a valid month."
      exit
   fi
   echo $M
}

# Retrieve month,day,year from a legal date
GetMonth() {
   echo ${1%%/*}
}

GetDay() {
   echo  | col / 2
}

GetYear() {
   echo ${1##*/}
}


AddToDate() {

   local Date=
   local days=
   local Month=`GetMonth $Date`
   local Day=`echo $Date | col / 2`   # Day of Date
   local Year=`echo $Date | col / 3`  # Year of Date
   local LeapYear=`IsLeapYear $Year`

   if [ $LeapYear = "yes" ]; then
      let Months[1]++
   fi
   Day=$[Day+days]
   while [ $Day -gt ${Months[$Month-1]} ]; do
       Day=$[Day -  ${Months[$Month-1]}]
       let Month++
   done
   echo "$Month/$Day/$Year"
}

# Convert a date to normal form
NormalizeDate () {
   Date=`echo "$*" | sed 'sX  *X/Xg'`
   local Day=`date +%d`
   local Month=`date +%m`
   local Year=`date +%Y`
   #echo Normalizing Date=$Date > /dev/tty
   case $Date in
      */*/* )
         Month=`echo $Date | col / 1 `
         Month=`Month2Int $Month`
         Day=`echo $Date | col / 2`
         Year=`echo $Date | col / 3`
         ;;
      */* )
         Month=`echo $Date | col / 1 `
         Month=`Month2Int $Month`
         Day=1
         Year=`echo $Date | col / 2 `
         ;;
      [a-z]* ) # Better be a month or day of week
         Exp=${Date:0:3}
         case $Exp in
            jan|feb|mar|apr|may|june|jul|aug|sep|oct|nov|dec )
               Month=$Exp
               Month=`Month2Int $Month`
               Day=1
               #Year stays the same
               ;;
            mon|tue|wed|thu|fri|sat|sun )
               # Compute the next such day
               local DayOfWeek=`date +%u`
               D=`Day2Int $Exp`
               if [ $DayOfWeek -le $D ]; then
                  Date=`AddToDate $Month/$Day/$Year $[D-DayOfWeek]`
               else
                  Date=`AddToDate $Month/$Day/$Year $[7+D-DayOfWeek]`
               fi

               # Reset Month/Day/Year
               Month=`echo $Date | col / 1 `
               Day=`echo $Date | col / 2`
               Year=`echo $Date | col / 3`
               ;;
            * ) echo "$Exp is not a valid month or day"
                exit
               ;;
            esac
         ;;
      * ) echo "$Date is not a valid date"
          exit
         ;;
   esac
   case $Day in
      [0-9]* );;  # Day must be numeric
      * ) echo "$Date is not a valid date"
          exit
         ;;
   esac
      [0-9][0-9][0-9][0-9] );;  # Year must be 4 digits
      [0-9][0-9] )
          Year=20$Year
      ;;
   esac
   Date=$Month/$Day/$Year
   echo $Date
}
# NormalizeDate jan
# NormalizeDate january
# NormalizeDate jan 2009
# NormalizeDate jan 22 1983
# NormalizeDate 1/22
# NormalizeDate 1 22
# NormalizeDate sat
# NormalizeDate sun
# NormalizeDate mon

ComputeExtension () {

   local Date=; shift
   local Month=`GetMonth $Date`
   local Day=`echo $Date | col / 2`
   local Year=`echo $Date | col / 3`
   local ExtensionExp="$*"
   case $ExtensionExp in
      *w*d* )  # like 5 weeks 3 days or even 5w2d
            ExtensionExp=`echo $ExtensionExp | sed 's/[a-z]/ /g'`
            weeks=`echo $ExtensionExp | col  1`
            days=`echo $ExtensionExp | col 2`
            days=$[7*weeks+days]
            Due=`AddToDate $Month/$Day/$Year $days`
      ;;
      *d )    # Like 5 days or 5d
            ExtensionExp=`echo $ExtensionExp | sed 's/[a-z]/ /g'`
            days=$ExtensionExp
            Due=`AddToDate $Month/$Day/$Year $days`
      ;;
      * )
            Due=$ExtensionExp
      ;;
   esac
   echo $Due

}


# Pop -- remove the first element from an array and shift left
Pop () {
   Var=
   eval "unset $Var[0]"
   eval "$Var=(${$Var[*]})"
}

ComputeDate () {
   local Date=`NormalizeDate `; shift
   local Expression=`echo $* | sed 's/^ *a /1 /;s/,/ /' | tr A-Z a-z `
   local Exp=(`echo $Expression `)
   local Token=$Exp  # first one
   local Ans=
   #echo "Computing date for ${Exp[*]}" > /dev/tty
   case $Token in
      */* ) # Regular date
         M=`GetMonth $Token`
         D=`GetDay $Token`
         Y=`GetYear $Token`
         if [ -z "$Y" ]; then
            Y=$Year
         elif [ ${#Y} -eq 2 ]; then
            Y=20$Y
         fi
         Ans="$M/$D/$Y"
         ;;
      yes* )
         Ans=`AddToDate $Date -1`
         ;;
      tod*|now )
         Ans=$Date
         ;;
      tom* )
         Ans=`AddToDate $Date 1`
         ;;
      the )
         case $Expression in
            *day*after* )  #the day after Date
               Pop Exp;   # Skip the
               Pop Exp;   # Skip day
               Pop Exp;   # Skip after
               #echo Calling ComputeDate $Date ${Exp[*]} > /dev/tty
               Date=`ComputeDate $Date ${Exp[*]}` #Recursive call
               #echo "New date is " $Date > /dev/tty
               Ans=`AddToDate $Date 1`
               ;;
            *last*day*of*th*month|*end*of*th*month )
               M=`date +%m`
               Day=${Months[M-1]}
               if [ $M -eq 2 -a `IsLeapYear $Year` = yes ]; then
                  let Day++
               fi
               Ans=$Month/$Day/$Year
               ;;
            *last*day*of* )
               D=${Expression##*of }
               D=`NormalizeDate $D`
               M=`GetMonth $D`
               Y=`GetYear $D`
               # echo M is $M > /dev/tty
               Day=${Months[M-1]}
               if [ $M -eq 2 -a `IsLeapYear $Y` = yes ]; then
                  let Day++
               fi
               Ans=$[M]/$Day/$Y
               ;;
            * )
               echo "Unknown expression: " $Expression
               exit
               ;;
         esac
         ;;
      next* ) # next DayOfWeek
         Pop Exp
         dow=`Day2Int $DayOfWeek` # First 3 chars
         tdow=`Day2Int ${Exp:0:3}` # First 3 chars
         n=$[7-dow+tdow]
         Ans=`AddToDate $Date $n`
         ;;
      this* )
         Pop Exp
         dow=`Day2Int $DayOfWeek`
         tdow=`Day2Int ${Exp:0:3}` # First 3 chars
         if [ $dow -gt $tdow ]; then
            echo "'this $Exp' has passed.  Did you mean 'next $Exp?'"
            exit
         fi
         n=$[tdow-dow]
         Ans=`AddToDate $Date $n`
         ;;
      [a-z]* ) # DayOfWeek ...

         M=${Exp:0:3}
         case $M in
            jan|feb|mar|apr|may|june|jul|aug|sep|oct|nov|dec )
               ND=`NormalizeDate ${Exp[*]}`
               Ans=$ND
               ;;
            mon|tue|wed|thu|fri|sat|sun )
               dow=`Day2Int $DayOfWeek`
               Ans=`NormalizeDate $Exp`

               if [ ${#Exp[*]} -gt 1 ]; then # Just a DayOfWeek
                  #tdow=`GetDay $Exp` # First 3 chars
                  #if [ $dow -gt $tdow ]; then
                     #echo "'this $Exp' has passed.  Did you mean 'next $Exp'?"
                     #exit
                  #fi
                  #n=$[tdow-dow]
               #else  # DayOfWeek in a future week
                  Pop Exp  # toss monday
                  Pop Exp  # toss in/off
                  if [ $Exp = next ]; then
                     Exp=2
                  fi
                  n=$[7*(Exp-1)]   # number of weeks
                  n=$[n+7-dow+tdow]
                  Ans=`AddToDate $Date $n`
               fi
               ;;
         esac
         ;;
      [0-9]* ) # Number  weeks [from|after] Date
         n=$Exp
         Pop Exp;
         case $Exp in
            w* ) let n=7*n;;
         esac

         Pop Exp; Pop Exp
         #echo Calling ComputeDate $Date ${Exp[*]} > /dev/tty
         Date=`ComputeDate $Date ${Exp[*]}` #Recursive call
         #echo "New date is " $Date > /dev/tty
         Ans=`AddToDate $Date $n`
         ;;
   esac
   echo $Ans
}

Year=`date +%Y`
Month=`date +%m`
Day=`date +%d`
DayOfWeek=`date +%a |tr A-Z a-z`

Date="$Month/$Day/$Year"
ComputeDate $Date $*

ce script utilise largement un autre script que j'ai écrit (appelé col ... de nombreuses excuses à ceux qui utilisent la norme col fourni avec Linux). Cette version de col simplifie l'extraction des colonnes du stdin. Ainsi,

$ echo a b c d e | col 5 3 2

imprime

e c b

Ici col script:

#!/bin/sh
# col -- extract columns from a file
# Usage:
#    col [-r] [c] col-1 col-2 ...
#   where [c] if supplied defines the field separator
#   where each col-i represents a column interpreted according to  the presence of -r as follows:
#        -r present : counting starts from the right end of the line
#        -r absent  : counting starts from the left side of the line
Separator=" "
Reverse=false
case "" in
 -r )  Reverse=true; shift;
 ;;
 [0-9]* )
 ;;
 * )Separator=""; shift;
 ;;
esac

case "" in
 -r )  Reverse=true; shift;
 ;;
 [0-9]* )
 ;;
 * )Separator=""; shift;
 ;;
esac

#  Replace each col-i with $i
Cols=""
for  f in $*
do
  if [ $Reverse = true ]; then
     Cols="$Cols $(NF-$f+1),"
  else
     Cols="$Cols $$f,"
  fi

done

Cols=`echo "$Cols" | sed 's/,$//'`
#echo "Using column specifications of $Cols"
awk -F "$Separator"  "{print $Cols}"

Il utilise aussi printdirections pour imprimer les directions quand le script est appelé mal:

#!/bin/sh
#
#  printdirections -- print header lines of a shell script
#
#  Usage:
#      printdirections path
#  where
#      path is a *full* path to the shell script in question
#      beginning with '/'
#
#  To use printdirections, you must include (as comments at the top
#  of your shell script) documentation for running the shell script.

if [ $# -eq 0 -o "$*" = "-h" ]; then
   printdirections 
   exit
fi
#  Delete the command invocation at the top of the file, if any
#  Delete from the place where printdirections occurs to the end of the file
#  Remove the # comments
#  There is a bizarre oddity here.
   sed '/#!/d;/.*printdirections/,$d;/ *#/!d;s/# //;s/#//'  > /tmp/printdirections.$$

#  Count the number of lines
numlines=`wc -l /tmp/printdirections.$$ | awk '{print }'`

#  Remove the last   line
numlines=`expr $numlines - 1`


head -n $numlines /tmp/printdirections.$$
rm /tmp/printdirections.$$

Pour utiliser ce lieu les trois scripts dans les fichiers ComputeDate, col et printdirections, respectivement. Placez le fichier dans le répertoire nommé par votre chemin, généralement ~/bin. Rendre exécutable avec:

$ chmod a+x ComputeDate col printdirections

Problèmes? Envoyez-moi un e-mail: morell AT cs.atu.edu Place ComputeDate dans le sujet.