history(1)




NAME

     history, fc - process command history list


SYNOPSIS

     /usr/bin/fc [ first [last]]

     /usr/bin/fc -l [-nr] [ first [last]]

     /usr/bin/fc -s [ old = new] [first]

  csh
     history [-hr] [n]

  ksh
     fc -e - [ old = new] [command]

     fc [-e ename] [-nlr] [ first [last]]


DESCRIPTION

  /usr/bin/fc
     The fc utility lists or edits and reexecutes, commands  pre-
     viously entered to an interactive sh.

     The command history list references commands by number.  The
     first  number in the list is selected arbitrarily. The rela-
     tionship of a number to its command will not  change  except
     when  the user logs in and no other process is accessing the
     list, at which time the system may reset  the  numbering  to
     start the oldest retained command at another number (usually
     1). When the number reaches the value  in  HISTSIZE  or  128
     (whichever  is  greater),  the  shell  may wrap the numbers,
     starting the next command with a lower number  (usually  1).
     However,  despite this optional wrapping of numbers, fc will
     maintain the time-ordering sequence  of  the  commands.  For
     example,  if four commands in sequence are given the numbers
     32766, 32767, 1 (wrapped), and 2 as they are executed,  com-
     mand  32767  is  considered  the command previous to 1, even
     though its number is higher.

     When commands are edited (when the -l option is  not  speci-
     fied), the resulting lines will be entered at the end of the
     history list and then reexecuted by sh. The fc command  that
     caused  the  editing  will  not  be entered into the history
     list. If the editor returns a  non-zero  exit  status,  this
     will  suppress  the entry into the history list and the com-
     mand reexecution.  Any command-line variable assignments  or
     redirection  operators  used with fc will affect both the fc
     command itself as well as  the  command  that  results,  for
     example:

     fc -s -- -1 2>/dev/null

     reinvokes the previous command, suppressing  standard  error
     for both fc and the previous command.

  csh
     Display the history list; if n is given, display only the  n
     most recent events.

     -r    Reverse the order of printout to be most recent  first
           rather than oldest first.

     -h    Display the history list without leading numbers. This
           is  used  to produce files suitable for sourcing using
           the -h option to the csh built-in command, source(1).

  History Substitution
     History substitution allows you to use words  from  previous
     command  lines in the command line you are typing. This sim-
     plifies spelling corrections and the repetition  of  compli-
     cated commands or arguments.  Command lines are saved in the
     history list, the size of which is controlled by the history
     variable.  The history shell variable may be set to the max-
     imum number of command lines that will be saved in the  his-
     tory file; i.e.:

     set history = 200

     will allow the history list to keep track of the most recent
     200  command  lines.  If not set, the C shell saves only the
     most recent command.

     A history substitution begins with a  !  (although  you  can
     change  this with the histchars variable) and may occur any-
     where on the command  line;  history  substitutions  do  not
     nest.  The  !  can be escaped with \ to suppress its special
     meaning.

     Input lines containing history substitutions are  echoed  on
     the terminal after being expanded, but before any other sub-
     stitutions take place or the command gets executed.

  Event Designators:
     An event designator is a reference to a command  line  entry
     in the history list.

     !     Start a history substitution, except when followed  by
           a space character, tab, newline, = or (.

     !!    Refer to the previous command. By itself, this substi-
           tution repeats the previous command.

     !n    Refer to command line n.

     !-n   Refer to the current command line minus n.

     !str  Refer to the most recent command starting with str.

     !?str?
           Refer to the most recent command containing str.

     !?str? additional
           Refer to the most recent command  containing  str  and
           append additional to that referenced command.

     !{command} additional
           Refer to the most recent command beginning  with  com-
           mand and append additional to that referenced command.

     ^previous_word^replacement^
           Repeat the previous command line replacing the  string
           previous_word  with  the  string  replacement. This is
           equivalent to the history substitution:

           !:s/previous_word/replacement/.

           To re-execute a specific  previous  command  AND  make
           such a substitution, say, re-executing command #6,

                !:6s/previous_word/replacement/.

  Word Designators:
     A `:' (colon) separates the  event  specification  from  the
     word  designator.  2It can be omitted if the word designator
     begins with a ^, $, *, - or %. If the word is to be selected
     from  the  previous  command,  the second ! character can be
     omitted from the event specification.   For  instance,  !!:1
     and  !:1  both  refer to the first word of the previous com-
     mand, while !!$ and !$ both refer to the last  word  in  the
     previous command. Word designators include:

          #     The entire command line typed so far.

          0     The first input word (command).

          n     The n'th argument.

          ^     The first argument, that is, 1.

          $     The last argument.

          %     The word matched by (the most recent) ?s search.

          x-y   A range of words; -y abbreviates 0-y.

          *     All the arguments, or a null value  if  there  is
                just one word in the event.

          x*    Abbreviates x-$.

          x-    Like x* but omitting word $.

  Modifiers:
     After the optional word designator, you can add  a  sequence
     of  one or more of the following modifiers, each preceded by
     a :.

     h     Remove a  trailing  pathname  component,  leaving  the
           head.

     r     Remove a trailing suffix of the form  `.xxx',  leaving
           the basename.

     e     Remove all but the suffix, leaving the extension.

     s/oldchars/replacements/ Substitute
           replacements for oldchars. oldchars is a  string  that
           may    contain    embedded   blank   spaces,   whereas
           previous_word in the event designator

           ^oldchars^replacements^

            may not.

           t     Remove all leading pathname components,  leaving
                 the tail.

           &     Repeat the previous substitution.

           g     Apply the change to the first  occurrence  of  a
                 match  in each word, by prefixing the above (for
                 example, g&).

           p     Print the new command but do not execute it.

           q     Quote the substituted  words,  escaping  further
                 substitutions.

           x     Like q, but break into words at each space char-
                 acter, tab or newline.

           Unless preceded by a g, the  modification  is  applied
           only  to  the  first  string that matches oldchars; an
           error results if no string matches.

           The left-hand side of substitutions  are  not  regular
           expressions,  but character strings. Any character can
           be used as the delimiter in place of  /.  A  backslash
           quotes  the  delimiter  character. The character &, in
           the right hand side, is replaced by the text from  the
           left-hand-side.  The & can be quoted with a backslash.
           A null oldchars uses the previous string either from a
           oldchars  or from a contextual scan string s from !?s.
           You can omit the  rightmost  delimiter  if  a  newline
           immediately follows replacements; the rightmost ? in a
           context scan can similarly be omitted.

           Without an event specification,  a  history  reference
           refers  either to the previous command, or to a previ-
           ous history reference on the command line (if any).

  ksh
     Using fc, in the form of

          fc -e - [ old=new ] [ command ],

     the command is re-executed after the substitution old=new is
     performed.  If  there  is  not  a command argument, the most
     recent command typed at this terminal is executed.

     Using fc in the form of

          fc [ -e ename ] [ -nlr ] [ first [ last ] ],

     a range of commands from first to last is selected from  the
     last HISTSIZE commands that were typed at the terminal.  The
     arguments first and last may be specified as a number or  as
     a string. A string is used to locate the most recent command
     starting with the given string.  A negative number  is  used
     as  an offset to the current command number.  If the -l flag
     is selected, the commands are  listed  on  standard  output.
     Otherwise,  the  editor program -e name is invoked on a file
     containing these keyboard commands.  If ename  is  not  sup-
     plied,  then  the  value  of  the  variable  FCEDIT (default
     /bin/ed) is used as the editor.  When editing  is  complete,
     the edited command(s) is executed.  If last is not specified
     then it will be set to first. If first is not specified  the
     default  is  the  previous  command  for editing and -16 for
     listing.
      The flag -r reverses the order of the commands and the flag

     -n  suppresses command numbers when listing. (See ksh(1) for
     more about command line editing.)

     HISTFILE
           If this variable is set when  the  shell  is  invoked,
           then  the  value is the pathname of the file that will
           be used to store the command history.

     HISTSIZE
           If this variable is set when  the  shell  is  invoked,
           then  the  number  of previously entered commands that
           are accessible by this shell will be greater  than  or
           equal to this number.  The default is 128.

  Command Re-entry:
     The text of the last HISTSIZE (default 128) commands entered
     from a terminal device is saved in a history file.  The file
     $HOME/.sh_history is used if the HISTFILE  variable  is  not
     set  or  if  the  file it names is not writable. A shell can
     access the commands of all interactive shells which use  the
     same named HISTFILE.  The special command fc is used to list
     or edit a portion of this file. The portion of the  file  to
     be  edited  or listed can be selected by number or by giving
     the first character or characters of the command.  A  single
     command or range of commands can be specified. If you do not
     specify an editor program as an  argument  to  fc  then  the
     value  of  the  variable  FCEDIT  is used.  If FCEDIT is not
     defined then /bin/ed  is  used.  The  edited  command(s)  is
     printed and re-executed upon leaving the editor.  The editor
     name - is used to skip the editing phase and  to  re-execute
     the  command.  In  this case a substitution parameter of the
     form old=new can be used to modify the command before execu-
     tion.  For example, if r is aliased to  'fc -e - ' then typ-
     ing `r bad=good c' will re-execute the most  recent  command
     which   starts  with  the  letter  c,  replacing  the  first
     occurrence of the string bad with the string good.

     Using the fc built-in command within a compound command will
     cause the whole command to disappear from the history file.


OPTIONS

     The following options are supported:

          -e  editor
                Use the editor named by editor to edit  the  com-
                mands.  The editor string is a utility name, sub-
                ject to search via the PATH variable.  The  value
                in  the FCEDIT variable is used as a default when
                -e is not specified. If FCEDIT is null or  unset,
                ed will be used as the editor.

          -l    (The letter ell.) List the commands  rather  than
                invoking  an editor on them. The commands will be
                written in the sequence indicated  by  the  first
                and  last  operands, as affected by -r, with each
                command preceded by the command number.

          -n    Suppress command numbers when listing with -l.

          -r    Reverse the order of the commands listed (with -l
                ) or edited (with neither -l nor -s).

          -s    Re-execute the command without invoking  an  edi-
                tor.


OPERANDS

     The following operands are supported:

     first

      last Select the commands to list or edit.   The  number  of
           previous  commands  that can be accessed is determined
           by the value of the HISTSIZE variable.  The  value  of
           first or last or both will be one of the following:

           [+]number
                 A positive number representing a command number;
                 command  numbers  can  be  displayed with the -l
                 option.

           -number
                 A negative decimal number representing the  com-
                 mand that was executed number of commands previ-
                 ously. For example, -1 is the immediately previ-
                 ous command.

           string
                 A string indicating the  most  recently  entered
                 command  that  begins  with  that string. If the
                 old=new operand is not also specified  with  -s,
                 the string form of the first operand cannot con-
                 tain an embedded equal sign.

                 When the synopsis form with -s is used:

                         o  If first  is  omitted,  the  previous
                            command will be used.
                 For the synopsis forms without -s :

                         o  If last is omitted, last defaults  to
                            the   previous  command  when  -l  is
                            specified; otherwise, it defaults  to
                            first.

                         o  If first and last are  both  omitted,
                            the  previous  16  commands  will  be
                            listed or the previous single command
                            will  be  edited  (based  on  the  -l
                            option).

                         o  If first and last are  both  present,
                            all  of  the  commands  from first to
                            last will be edited (without -l )  or
                            listed  (with  -l).  Editing multiple
                            commands  will  be  accomplished   by
                            presenting  to  the editor all of the
                            commands at one  time,  each  command
                            starting  on  a  new  line.  If first
                            represents a newer command than last,
                            the commands will be listed or edited
                            in reverse  sequence,  equivalent  to
                            using -r . For example, the following
                            commands  on  the  first   line   are
                            equivalent  to the corresponding com-
                            mands on the second:

                            fc -r 10 20     fc    30 40
                            fc   20 10      fc -r 40 30

                               o  When a  range  of  commands  is
                                  used,  it  will not be an error
                                  to specify first or last values
                                  that  are  not  in  the history
                                  list; fc  will  substitute  the
                                  value  representing  the oldest
                                  or newest command in the  list,
                                  as appropriate. For example, if
                                  there are only ten commands  in
                                  the history list, numbered 1 to
                                  10:

                                  fc -l
                                  fc 1 99

                                  will  list  and  edit,  respec-
                                  tively, all ten commands.

                      old=new
                            Replace  the  first   occurrence   of
                            string  old  in  the  commands  to be
                            reexecuted by the string new.


OUTPUT

     When the -l option is used to list commands, the  format  of
     each command in the list is as follows:

     "%d\t%s\n", <line number>, <command>

     If both the -l and -n options are specified, the  format  of
     each command is:

     "\t%s\n", <command>

     If the commandcommand consists of more than  one  line,  the
     lines after the first are displayed as:

     "\t%s\n", <continued-command>


EXAMPLES

     Example 1: Using history and fc

                  csh                                     ksh

     % history                               $ fc -l
       1   cd /etc                             1   cd /etc
       2   vi passwd                           2   vi passwd
       3   date                                3   date
       4   cd                                  4   cd
       5   du .                                5   du .
       6   ls -t                               6   ls -t
       7   history                             7   fc -l

     % !d                                    $ fc -e - d
       du .                                    du .
       262   ./SCCS                            262   ./SCCS
       336   .                                 336   .

     % !da                                   $ fc -e - da
       Thu Jul 21 17:29:56 PDT 1994            Thu Jul 21 17:29:56 PDT 1994

     %                                       $ alias \!='fc -e -'

     % !!                                    $ !
       date                                    alias ='fc -e -'
       Thu Jul 21 17:29:56 PDT 1994


ENVIRONMENT VARIABLES

     See environ(5) for descriptions of the following environment
     variables   that  affect  the  execution  of  fc:  LC_CTYPE,
     LC_MESSAGES, and NLSPATH.
     FCEDIT
           This variable, when expanded by the shell,  determines
           the  default  value  for  the e editor option's editor
           option-argument. If FCEDIT is null or unset,  ed  will
           be used as the editor.

     HISTFILE
           Determine a pathname naming a command history file. If
           the  HISTFILE  variable  is  not  set,  the  shell may
           attempt to access or create a file .sh_history in  the
           user's home directory. If the shell cannot obtain both
           read and write access to, or create, the history file,
           it  will  use an unspecified mechanism that allows the
           history to operate properly.  (References  to  history
           ``file''  in  this section are understood to mean this
           unspecified mechanism in such cases.) fc may choose to
           access  this  variable only when initializing the his-
           tory file; this initialization will occur when  fc  or
           sh  first  attempt  to  retrieve  entries from, or add
           entries to, the file, as the result of commands issued
           by  the user, the file named by the ENV variable, or a
           system startup file such as  /etc/profile.  (The  ini-
           tialization process for the history file can be depen-
           dent on the system startup files,  in  that  they  may
           contain  commands  that  will  effectively preempt the
           user's settings of HISTFILE and HISTSIZE. For example,
           function  definition commands are recorded in the his-
           tory file, unless the set -o nolog option is  set.  If
           the system administrator includes function definitions
           in some system startup  file  called  before  the  ENV
           file,  the history file will be initialized before the
           user gets a chance to influence its  characteristics.)
           The  variable  HISTFILE is accessed initially when the
           shell is invoked. Any changes  to  HISTFILE  will  not
           take effect until another shell is invoked.

     HISTSIZE
           Determine a decimal number representing the  limit  to
           the  number  of previous commands that are accessible.
           If this variable  is  unset,  an  unspecified  default
           greater  than  or equal to 128 will be used. The vari-
           able HISTSIZE is accessed initially when the shell  is
           invoked.  Any changes to HISTSIZE will not take effect
           until another shell is invoked.


EXIT STATUS

     The following exit values are returned:

     0     Successful completion of the listing.

     >0    An error occurred.

     Otherwise, the exit status will be that of the commands exe-
     cuted by fc.


ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWcsu                     |
    |_____________________________|_____________________________|


SEE ALSO

     csh(1), ed(1), ksh(1), set(1),  set(1F),  sh(1),  source(1),
     attributes(5), environ(5)


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