fc - Processes the command history list
fc [-r] [-e editor] [first[last]]
fc -l [-nr] [first[last]]
fc [-s] [old=new] [first]
Interfaces documented on this reference page conform to
industry standards as follows:
fc: XCU5.0
Refer to the standards(5) reference page for more information
about industry standards and associated tags.
Uses the editor named by editor to edit the commands. The
editor string is a utility name, subject 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 is used as the editor. Lists the commands
rather than invoking an editor on them. The commands are
written in the sequence indicated by the first and last
parameters, as affected by -r, with each command preceded
by the command number. Suppresses command numbers when
listing with -l. Reverses the order of the commands
listed (with -l) or edited (with neither -l nor -s).
Reexecutes the command without invoking an editor.
Selects 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 is one of the following: A positive number
representing a command number; command numbers can be displayed
with the -l option. A negative decimal number representing
the command that was executed number of commands
previously. For example, -1 is the immediately previous
command. 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 contain an embedded equal sign.
When the synopsis form with -s is used: If first is
omitted, the previous command is used.
For the synopsis forms without -s: If last is omitted,
last defaults to the previous command when -l
is specified; otherwise, it defaults to first. If
first and last are both omitted, the previous 16
commands are listed or the previous single command
is edited (based on the -l option). If first and
last are both present, all of the commands from
first to last are edited (without -l) or listed
(with -l). Editing multiple commands is 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 are listed or edited in reverse
sequence, equivalent to using -r. For example, the
following commands on the first line are equivalent
to the corresponding commands on the second:
fc -r 10 20 fc 30 40 fc 20
10 fc -r 40 30 When a range of
commands is used, it is not an error to specify
first or last values that are not in the history
list; fc substitutes 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, the following
commands list and edit, respectively, all ten
commands:
fc -l fc 1 99
The first occurrence of string old in the commands
to be reexecuted is replaced by the string new.
The fc utility lists or edits and reexecutes commands previously
entered to an interactive shell.
The command history list references commands by number.
The first number in the list is selected arbitrarily. The
relationship of a number to its command does 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 an upper
limit, either the value in HISTSIZE or 32767 (whichever is
greater), the shell wraps the numbers, starting the next
command with number 1. However, despite this optional
wrapping of numbers, fc maintains 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, command 32767 is considered
the command previous to 1, even though its number is
higher.
When commands are edited (when the -l option is not specified),
the resulting lines are entered at the end of the
history list and then reexecuted by sh. The fc command
that caused the editing is not entered into the history
list. If the editor returns a non-zero exit status, this
suppresses the entry into the history list and the command
reexecution. Any command-line variable assignments or
redirection operators used with fc affect both the fc command
itself as well as the command that results. The following
command reinvokes the previous command, suppressing
standard error for both fc and the previous command: fc -s
-- -1 2>/dev/null
Users on windowing systems may want to have separate history
files for each window by setting HISTFILE to the following:
HISTFILE=$HOME/.sh_hist$$
Since editors sometimes use file descriptors as integral
parts of their editing, redirecting their file descriptors
as part of the fc command can produce unexpected results.
For example, if vi is the FCEDIT editor, the following
command will not work correctly on many systems: fc -s |
more
The following exit values are returned: Successful completion
of the listing. An error occurred.
Otherwise, the exit status is that of the commands executed
by fc.
ENVIRONMENT VARIABLES [Toc] [Back] The following environment variables affect the execution
of fc: 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 is used
as the editor. Determines a path name naming a command
history file. If the HISTFILE variable is not set, the
shell attempts to access or create a file in your home
directory. If the shell cannot obtain both read and write
access to, or create, the history file, it uses a default
mechanism that allows the history to operate properly.
Changes made to HISTFILE after the history file has been
initialized are not effective. If more than one instance
of the shell is using the same history file, it is unspecified
how updates to the history file from those shells
interact. As entries are deleted from the history file,
they will be deleted oldest first. Determines a decimal
number representing the limit to the number of previous
commands that are accessible. If this variable is unset, a
default of 128 is used. Changes made to HISTSIZE after
the history file has been initialized are not effective.
Provides a default value for the internationalization
variables that are unset or null. If LANG is unset or
null, the corresponding value from the default locale is
used. If any of the internationalization variables contain
an invalid setting, the utility behaves as if none of
the variables had been defined. If set to a non-empty
string value, overrides the values of all the other internationalization
variables. Determines the locale for the
interpretation of sequences of bytes of text data as characters
(for example, single-byte as opposed to multibyte
characters in arguments and input files). Determines the
locale used to affect the format and contents of diagnostic
messages written to standard error. Determines the
location of message catalogues for the processing of
LC_MESSAGES.
Commands: sh(1p)
Standards: standards(5)
fc(1)
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