YESTERDAY(1)                                         YESTERDAY(1)

     NAME
          yesterday, diffy - print file names from the dump

     SYNOPSIS
          yesterday [ -abcCdDs ] [ -n daysago ] [ -date ] files ...

          diffy [ -abcefmnrw ] files ...

     DESCRIPTION
          Yesterday prints the names of the files from the most recent
          dump.  Since dumps are done early in the morning,
          yesterday's files are really in today's dump.  For example,
          if today is March 17, 1992,

               yesterday /adm/users

          prints

               /n/dump/1992/0317/adm/users

          In fact, the implementation is to select the most recent
          dump in the current year, so the dump selected may not be
          from today.

          When presented with a path of the form /n/fs/path, yesterday
          will look for dump files of the form
          /n/fsdump/yyyy/hhmm/path.

          By default, yesterday prints the names of the dump files
          corresponding to the named files.  The first set of options
          changes this behavior.

          -a   Run acme(1)'s adiff to compare the dump files with the
               named files.

          -b   Bind the dump files over the named files.

          -c   Copy the dump files over the named files.

          -C   Copy the dump files over the named files only when they
               differ.

          -d   Run diff to compare the dump files with the named
               files.

          -D   Run diff -n to compare the dump files with the named
               files.

          The date option selects other day's dumps, with a format of
          1, 2, 4, 6, or 8 digits of the form d, dd, mmdd, yymmdd, or

     YESTERDAY(1)                                         YESTERDAY(1)

          yyyymmdd.

          The -n option selects the dump daysago prior to the current
          day.

          The -s option selects the most recent snapshot instead of
          the most recent archived dump.  Snapshots may occur more
          frequently than dumps.

          Yesterday does not guarantee that the string it prints rep-
          resents an existing file.

          Diffy runs diff(1) with the given options to compare
          yesterday's version of each of the named files with today's.

     EXAMPLES
          Back up to yesterday's MIPS binary of vc:

               yesterday -c /mips/bin/vc

          Temporarily back up to March 1's MIPS C library to see if a
          program runs correctly when loaded with it:

               yesterday -b -0301 /mips/lib/libc.a
               rm v.out
               mk
               v.out

          Find what has changed in the C library since March 1:

               yesterday -d -0301 /sys/src/libc/port/*.c

          Find what has changed in the source tree today:

               diffy -r /sys/src

     FILES
          /n/dump

     SOURCE
          /rc/bin/yesterday
          /rc/bin/diffy

     SEE ALSO
          history(1), bind(1), diff(1), fs(4).

     BUGS
          It's hard to use this command without singing.

          Doesn't work on January 1st.