See Chapter 2, Shell Command Language. The functionality
described in the rest of the EXTENDED DESCRIPTION section shall
be provided on implementations that support the User Portability
Utilities option (and the rest of this section is not further
shaded for this option).
Command History List
When the sh utility is being used interactively, it shall
maintain a list of commands previously entered from the terminal
in the file named by the HISTFILE environment variable. The type,
size, and internal format of this file are unspecified. Multiple
sh processes can share access to the file for a user, if file
access permissions allow this; see the description of the
HISTFILE environment variable.
Command Line Editing
When sh is being used interactively from a terminal, the current
command and the command history (see fc(1p)) can be edited using
vi-mode command line editing. This mode uses commands, described
below, similar to a subset of those described in the vi utility.
Implementations may offer other command line editing modes
corresponding to other editing utilities.
The command set -o vi shall enable vi-mode editing and place sh
into vi insert mode (see Command Line Editing (vi-mode)). This
command also shall disable any other editing mode that the
implementation may provide. The command set +o vi disables vi-
mode editing.
Certain block-mode terminals may be unable to support shell
command line editing. If a terminal is unable to provide either
edit mode, it need not be possible to set -o vi when using the
shell on this terminal.
In the following sections, the characters erase, interrupt, kill,
and end-of-file are those set by the stty utility.
Command Line Editing (vi-mode)
In vi editing mode, there shall be a distinguished line, the edit
line. All the editing operations which modify a line affect the
edit line. The edit line is always the newest line in the command
history buffer.
With vi-mode enabled, sh can be switched between insert mode and
command mode.
When in insert mode, an entered character shall be inserted into
the command line, except as noted in vi Line Editing Insert Mode.
Upon entering sh and after termination of the previous command,
sh shall be in insert mode.
Typing an escape character shall switch sh into command mode (see
vi Line Editing Command Mode). In command mode, an entered
character shall either invoke a defined operation, be used as
part of a multi-character operation, or be treated as an error. A
character that is not recognized as part of an editing command
shall terminate any specific editing command and shall alert the
terminal. If sh receives a SIGINT signal in command mode (whether
generated by typing the interrupt character or by other means),
it shall terminate command line editing on the current command
line, reissue the prompt on the next line of the terminal, and
reset the command history (see fc(1p)) so that the most recently
executed command is the previous command (that is, the command
that was being edited when it was interrupted is not re-entered
into the history).
In the following sections, the phrase ``move the cursor to the
beginning of the word'' shall mean ``move the cursor to the first
character of the current word'' and the phrase ``move the cursor
to the end of the word'' shall mean ``move the cursor to the last
character of the current word''. The phrase ``beginning of the
command line'' indicates the point between the end of the prompt
string issued by the shell (or the beginning of the terminal
line, if there is no prompt string) and the first character of
the command text.
vi Line Editing Insert Mode
While in insert mode, any character typed shall be inserted in
the current command line, unless it is from the following set.
<newline> Execute the current command line. If the current
command line is not empty, this line shall be entered
into the command history (see fc(1p)).
erase Delete the character previous to the current cursor
position and move the current cursor position back one
character. In insert mode, characters shall be erased
from both the screen and the buffer when backspacing.
interrupt If sh receives a SIGINT signal in insert mode (whether
generated by typing the interrupt character or by other
means), it shall terminate command line editing with
the same effects as described for interrupting command
mode; see Command Line Editing (vi-mode).
kill Clear all the characters from the input line.
<control>‐V
Insert the next character input, even if the character
is otherwise a special insert mode character.
<control>‐W
Delete the characters from the one preceding the cursor
to the preceding word boundary. The word boundary in
this case is the closer to the cursor of either the
beginning of the line or a character that is in neither
the blank nor punct character classification of the
current locale.
end-of-file
Interpreted as the end of input in sh. This
interpretation shall occur only at the beginning of an
input line. If end-of-file is entered other than at the
beginning of the line, the results are unspecified.
<ESC> Place sh into command mode.
vi Line Editing Command Mode
In command mode for the command line editing feature, decimal
digits not beginning with 0 that precede a command letter shall
be remembered. Some commands use these decimal digits as a count
number that affects the operation.
The term motion command represents one of the commands:
<space> 0 b F l W ^ $ ; E f T w | , B e h t
If the current line is not the edit line, any command that
modifies the current line shall cause the content of the current
line to replace the content of the edit line, and the current
line shall become the edit line. This replacement cannot be
undone (see the u and U commands below). The modification
requested shall then be performed to the edit line. When the
current line is the edit line, the modification shall be done
directly to the edit line.
Any command that is preceded by count shall take a count (the
numeric value of any preceding decimal digits). Unless otherwise
noted, this count shall cause the specified operation to repeat
by the number of times specified by the count. Also unless
otherwise noted, a count that is out of range is considered an
error condition and shall alert the terminal, but neither the
cursor position, nor the command line, shall change.
The terms word and bigword are used as defined in the vi
description. The term save buffer corresponds to the term unnamed
buffer in vi.
The following commands shall be recognized in command mode:
<newline> Execute the current command line. If the current
command line is not empty, this line shall be entered
into the command history (see fc(1p)).
<control>‐L
Redraw the current command line. Position the cursor at
the same location on the redrawn line.
# Insert the character '#' at the beginning of the
current command line and treat the resulting edit line
as a comment. This line shall be entered into the
command history; see fc(1p).
= Display the possible shell word expansions (see Section
2.6, Word Expansions) of the bigword at the current
command line position.
Note: This does not modify the content of the current
line, and therefore does not cause the current
line to become the edit line.
These expansions shall be displayed on subsequent
terminal lines. If the bigword contains none of the
characters '?', '*', or '[', an <asterisk> ('*') shall
be implicitly assumed at the end. If any directories
are matched, these expansions shall have a '/'
character appended. After the expansion, the line shall
be redrawn, the cursor repositioned at the current
cursor position, and sh shall be placed in command
mode.
\ Perform pathname expansion (see Section 2.6.6, Pathname
Expansion) on the current bigword, up to the largest
set of characters that can be matched uniquely. If the
bigword contains none of the characters '?', '*', or
'[', an <asterisk> ('*') shall be implicitly assumed at
the end. This maximal expansion then shall replace the
original bigword in the command line, and the cursor
shall be placed after this expansion. If the resulting
bigword completely and uniquely matches a directory, a
'/' character shall be inserted directly after the
bigword. If some other file is completely matched, a
single <space> shall be inserted after the bigword.
After this operation, sh shall be placed in insert
mode.
* Perform pathname expansion on the current bigword and
insert all expansions into the command to replace the
current bigword, with each expansion separated by a
single <space>. If at the end of the line, the current
cursor position shall be moved to the first column
position following the expansions and sh shall be
placed in insert mode. Otherwise, the current cursor
position shall be the last column position of the first
character after the expansions and sh shall be placed
in insert mode. If the current bigword contains none of
the characters '?', '*', or '[', before the operation,
an <asterisk> ('*') shall be implicitly assumed at the
end.
@letter Insert the value of the alias named _letter. The
symbol letter represents a single alphabetic character
from the portable character set; implementations may
support additional characters as an extension. If the
alias _letter contains other editing commands, these
commands shall be performed as part of the insertion.
If no alias _letter is enabled, this command shall have
no effect.
[count]~ Convert, if the current character is a lowercase
letter, to the equivalent uppercase letter and vice
versa, as prescribed by the current locale. The current
cursor position then shall be advanced by one
character. If the cursor was positioned on the last
character of the line, the case conversion shall occur,
but the cursor shall not advance. If the '~' command is
preceded by a count, that number of characters shall be
converted, and the cursor shall be advanced to the
character position after the last character converted.
If the count is larger than the number of characters
after the cursor, this shall not be considered an
error; the cursor shall advance to the last character
on the line.
[count]. Repeat the most recent non-motion command, even if it
was executed on an earlier command line. If the
previous command was preceded by a count, and no count
is given on the '.' command, the count from the
previous command shall be included as part of the
repeated command. If the '.' command is preceded by a
count, this shall override any count argument to the
previous command. The count specified in the '.'
command shall become the count for subsequent '.'
commands issued without a count.
[number]v Invoke the vi editor to edit the current command line
in a temporary file. When the editor exits, the
commands in the temporary file shall be executed and
placed in the command history. If a number is included,
it specifies the command number in the command history
to be edited, rather than the current command line.
[count]l (ell)
[count]<space>
Move the current cursor position to the next character
position. If the cursor was positioned on the last
character of the line, the terminal shall be alerted
and the cursor shall not be advanced. If the count is
larger than the number of characters after the cursor,
this shall not be considered an error; the cursor shall
advance to the last character on the line.
[count]h Move the current cursor position to the countth
(default 1) previous character position. If the cursor
was positioned on the first character of the line, the
terminal shall be alerted and the cursor shall not be
moved. If the count is larger than the number of
characters before the cursor, this shall not be
considered an error; the cursor shall move to the first
character on the line.
[count]w Move to the start of the next word. If the cursor was
positioned on the last character of the line, the
terminal shall be alerted and the cursor shall not be
advanced. If the count is larger than the number of
words after the cursor, this shall not be considered an
error; the cursor shall advance to the last character
on the line.
[count]W Move to the start of the next bigword. If the cursor
was positioned on the last character of the line, the
terminal shall be alerted and the cursor shall not be
advanced. If the count is larger than the number of
bigwords after the cursor, this shall not be considered
an error; the cursor shall advance to the last
character on the line.
[count]e Move to the end of the current word. If at the end of a
word, move to the end of the next word. If the cursor
was positioned on the last character of the line, the
terminal shall be alerted and the cursor shall not be
advanced. If the count is larger than the number of
words after the cursor, this shall not be considered an
error; the cursor shall advance to the last character
on the line.
[count]E Move to the end of the current bigword. If at the end
of a bigword, move to the end of the next bigword. If
the cursor was positioned on the last character of the
line, the terminal shall be alerted and the cursor
shall not be advanced. If the count is larger than the
number of bigwords after the cursor, this shall not be
considered an error; the cursor shall advance to the
last character on the line.
[count]b Move to the beginning of the current word. If at the
beginning of a word, move to the beginning of the
previous word. If the cursor was positioned on the
first character of the line, the terminal shall be
alerted and the cursor shall not be moved. If the count
is larger than the number of words preceding the
cursor, this shall not be considered an error; the
cursor shall return to the first character on the line.
[count]B Move to the beginning of the current bigword. If at the
beginning of a bigword, move to the beginning of the
previous bigword. If the cursor was positioned on the
first character of the line, the terminal shall be
alerted and the cursor shall not be moved. If the count
is larger than the number of bigwords preceding the
cursor, this shall not be considered an error; the
cursor shall return to the first character on the line.
^ Move the current cursor position to the first character
on the input line that is not a <blank>.
$ Move to the last character position on the current
command line.
0 (Zero.) Move to the first character position on the
current command line.
[count]| Move to the countth character position on the current
command line. If no number is specified, move to the
first position. The first character position shall be
numbered 1. If the count is larger than the number of
characters on the line, this shall not be considered an
error; the cursor shall be placed on the last character
on the line.
[count]fc Move to the first occurrence of the character 'c' that
occurs after the current cursor position. If the cursor
was positioned on the last character of the line, the
terminal shall be alerted and the cursor shall not be
advanced. If the character 'c' does not occur in the
line after the current cursor position, the terminal
shall be alerted and the cursor shall not be moved.
[count]Fc Move to the first occurrence of the character 'c' that
occurs before the current cursor position. If the
cursor was positioned on the first character of the
line, the terminal shall be alerted and the cursor
shall not be moved. If the character 'c' does not occur
in the line before the current cursor position, the
terminal shall be alerted and the cursor shall not be
moved.
[count]tc Move to the character before the first occurrence of
the character 'c' that occurs after the current cursor
position. If the cursor was positioned on the last
character of the line, the terminal shall be alerted
and the cursor shall not be advanced. If the character
'c' does not occur in the line after the current cursor
position, the terminal shall be alerted and the cursor
shall not be moved.
[count]Tc Move to the character after the first occurrence of the
character 'c' that occurs before the current cursor
position. If the cursor was positioned on the first
character of the line, the terminal shall be alerted
and the cursor shall not be moved. If the character 'c'
does not occur in the line before the current cursor
position, the terminal shall be alerted and the cursor
shall not be moved.
[count]; Repeat the most recent f, F, t, or T command. Any
number argument on that previous command shall be
ignored. Errors are those described for the repeated
command.
[count], Repeat the most recent f, F, t, or T command. Any
number argument on that previous command shall be
ignored. However, reverse the direction of that
command.
a Enter insert mode after the current cursor position.
Characters that are entered shall be inserted before
the next character.
A Enter insert mode after the end of the current command
line.
i Enter insert mode at the current cursor position.
Characters that are entered shall be inserted before
the current character.
I Enter insert mode at the beginning of the current
command line.
R Enter insert mode, replacing characters from the
command line beginning at the current cursor position.
[count]cmotion
Delete the characters between the current cursor
position and the cursor position that would result from
the specified motion command. Then enter insert mode
before the first character following any deleted
characters. If count is specified, it shall be applied
to the motion command. A count shall be ignored for the
following motion commands:
0 ^ $ c
If the motion command is the character 'c', the current
command line shall be cleared and insert mode shall be
entered. If the motion command would move the current
cursor position toward the beginning of the command
line, the character under the current cursor position
shall not be deleted. If the motion command would move
the current cursor position toward the end of the
command line, the character under the current cursor
position shall be deleted. If the count is larger than
the number of characters between the current cursor
position and the end of the command line toward which
the motion command would move the cursor, this shall
not be considered an error; all of the remaining
characters in the aforementioned range shall be deleted
and insert mode shall be entered. If the motion command
is invalid, the terminal shall be alerted, the cursor
shall not be moved, and no text shall be deleted.
C Delete from the current character to the end of the
line and enter insert mode at the new end-of-line.
S Clear the entire edit line and enter insert mode.
[count]rc Replace the current character with the character 'c'.
With a number count, replace the current and the
following count-1 characters. After this command, the
current cursor position shall be on the last character
that was changed. If the count is larger than the
number of characters after the cursor, this shall not
be considered an error; all of the remaining characters
shall be changed.
[count]_ Append a <space> after the current character position
and then append the last bigword in the previous input
line after the <space>. Then enter insert mode after
the last character just appended. With a number count,
append the countth bigword in the previous line.
[count]x Delete the character at the current cursor position and
place the deleted characters in the save buffer. If the
cursor was positioned on the last character of the
line, the character shall be deleted and the cursor
position shall be moved to the previous character (the
new last character). If the count is larger than the
number of characters after the cursor, this shall not
be considered an error; all the characters from the
cursor to the end of the line shall be deleted.
[count]X Delete the character before the current cursor position
and place the deleted characters in the save buffer.
The character under the current cursor position shall
not change. If the cursor was positioned on the first
character of the line, the terminal shall be alerted,
and the X command shall have no effect. If the line
contained a single character, the X command shall have
no effect. If the line contained no characters, the
terminal shall be alerted and the cursor shall not be
moved. If the count is larger than the number of
characters before the cursor, this shall not be
considered an error; all the characters from before the
cursor to the beginning of the line shall be deleted.
[count]dmotion
Delete the characters between the current cursor
position and the character position that would result
from the motion command. A number count repeats the
motion command count times. If the motion command would
move toward the beginning of the command line, the
character under the current cursor position shall not
be deleted. If the motion command is d, the entire
current command line shall be cleared. If the count is
larger than the number of characters between the
current cursor position and the end of the command line
toward which the motion command would move the cursor,
this shall not be considered an error; all of the
remaining characters in the aforementioned range shall
be deleted. The deleted characters shall be placed in
the save buffer.
D Delete all characters from the current cursor position
to the end of the line. The deleted characters shall be
placed in the save buffer.
[count]ymotion
Yank (that is, copy) the characters from the current
cursor position to the position resulting from the
motion command into the save buffer. A number count
shall be applied to the motion command. If the motion
command would move toward the beginning of the command
line, the character under the current cursor position
shall not be included in the set of yanked characters.
If the motion command is y, the entire current command
line shall be yanked into the save buffer. The current
cursor position shall be unchanged. If the count is
larger than the number of characters between the
current cursor position and the end of the command line
toward which the motion command would move the cursor,
this shall not be considered an error; all of the
remaining characters in the aforementioned range shall
be yanked.
Y Yank the characters from the current cursor position to
the end of the line into the save buffer. The current
character position shall be unchanged.
[count]p Put a copy of the current contents of the save buffer
after the current cursor position. The current cursor
position shall be advanced to the last character put
from the save buffer. A count shall indicate how many
copies of the save buffer shall be put.
[count]P Put a copy of the current contents of the save buffer
before the current cursor position. The current cursor
position shall be moved to the last character put from
the save buffer. A count shall indicate how many copies
of the save buffer shall be put.
u Undo the last command that changed the edit line. This
operation shall not undo the copy of any command line
to the edit line.
U Undo all changes made to the edit line. This operation
shall not undo the copy of any command line to the edit
line.
[count]k
[count]- Set the current command line to be the countth previous
command line in the shell command history. If count is
not specified, it shall default to 1. The cursor shall
be positioned on the first character of the new
command. If a k or - command would retreat past the
maximum number of commands in effect for this shell
(affected by the HISTSIZE environment variable), the
terminal shall be alerted, and the command shall have
no effect.
[count]j
[count]+ Set the current command line to be the countth next
command line in the shell command history. If count is
not specified, it shall default to 1. The cursor shall
be positioned on the first character of the new
command. If a j or + command advances past the edit
line, the current command line shall be restored to the
edit line and the terminal shall be alerted.
[number]G Set the current command line to be the oldest command
line stored in the shell command history. With a number
number, set the current command line to be the command
line number in the history. If command line number does
not exist, the terminal shall be alerted and the
command line shall not be changed.
/pattern<newline>
Move backwards through the command history, searching
for the specified pattern, beginning with the previous
command line. Patterns use the pattern matching
notation described in Section 2.13, Pattern Matching
Notation, except that the '^' character shall have
special meaning when it appears as the first character
of pattern. In this case, the '^' is discarded and the
characters after the '^' shall be matched only at the
beginning of a line. Commands in the command history
shall be treated as strings, not as filenames. If the
pattern is not found, the current command line shall be
unchanged and the terminal shall be alerted. If it is
found in a previous line, the current command line
shall be set to that line and the cursor shall be set
to the first character of the new command line.
If pattern is empty, the last non-empty pattern
provided to / or ? shall be used. If there is no
previous non-empty pattern, the terminal shall be
alerted and the current command line shall remain
unchanged.
?pattern<newline>
Move forwards through the command history, searching
for the specified pattern, beginning with the next
command line. Patterns use the pattern matching
notation described in Section 2.13, Pattern Matching
Notation, except that the '^' character shall have
special meaning when it appears as the first character
of pattern. In this case, the '^' is discarded and the
characters after the '^' shall be matched only at the
beginning of a line. Commands in the command history
shall be treated as strings, not as filenames. If the
pattern is not found, the current command line shall be
unchanged and the terminal shall be alerted. If it is
found in a following line, the current command line
shall be set to that line and the cursor shall be set
to the fist character of the new command line.
If pattern is empty, the last non-empty pattern
provided to / or ? shall be used. If there is no
previous non-empty pattern, the terminal shall be
alerted and the current command line shall remain
unchanged.
n Repeat the most recent / or ? command. If there is no
previous / or ?, the terminal shall be alerted and the
current command line shall remain unchanged.
N Repeat the most recent / or ? command, reversing the
direction of the search. If there is no previous / or
?, the terminal shall be alerted and the current
command line shall remain unchanged.
