Linux Commands 彻底研究（03）：tput
NAME
tput, reset - initialize a terminal or query terminfo database
SYNOPSIS
tput [-Ttype] capname [parms ... ]
tput [-Ttype] init
tput [-Ttype] reset
tput [-Ttype]
longname
tput -S <<
tput -V
DESCRIPTION
The tput utility uses the terminfo
database to make the values of terminal-dependent capabilities and information
available to the shell (see sh(1)), to initialize or reset the
terminal, or return the long name of the requested terminal type. The
result depends upon the capability’s type:
string
tput writes the string to the
standard output. No trailing newline is supplied.
integer
tput writes the decimal value to
the standard output, with a trailing newline.
boolean
tput simply sets the exit code
(0 for TRUE if the terminal has the capability, 1 for FALSE if it does
not), and writes nothing to the standard output.
Before using a value returned on the standard output, the
application should test the exit code (e.g., $?, see sh(1)) to be sure it
is 0.
(See the EXIT CODES and DIAGNOSTICS sections.) For a
complete list of capabilities and the capname associated with each, see
terminfo(5).
-Ttype indicates the type of terminal. Normally this option is unnecessary, because the default is taken from the environment variable TERM. If -T is specified, then the shell variables LINES and COLUMNS will be ignored,and the operating system will not be queried for the actual screen size.
capname
indicates the capability from the terminfo
database. When termcap support is compiled in, the termcap name for the
capability is also accepted.
parms If the capability is a string that takes parameters, the arguments parms will be instantiated into the string.
Most parameters are numbers. Only a few terminfo capabilities require string parameters; tput uses a table to decide which to pass as strings. Normally tput uses tparm (3X) to perform the substitution. If no parameters are given for the capability, tput writes the string without performing the substitution.
-S allows more than one capability per invocation of tput.
The capabilities must be passed to tput from the standard
input instead of from the command line (see example). Only one capname
is allowed per line. The -S option changes the meaning of the 0 and 1
boolean and string exit codes (see the EXIT CODES
section).
Again, tput uses a table and the presence of parameters in its input to decide whether to use tparm (3X), and how to interpret the parameters.
-V reports the version of ncurses which was used in this program, and exits.
init If the terminfo database is present and an entry for the user’s terminal exists (see -Ttype, above), the following will occur:
(1) if present, the terminal’s initialization strings will be output as detailed in the terminfo(5) section on Tabs and Initialization,
(2) any delays (e.g., newline) specified in the entry will be set in the tty driver,
(3) tabs expansion will be turned on or off according to the specification in the entry, and
(4) if tabs are not expanded, standard tabs will be set (every 8 spaces).
If an entry does not contain the information needed for any of the four above activities, that activity will silently be skipped.
reset Instead of putting out initialization strings, the
terminal’s
reset strings will be output if present (rs1, rs2,
rs3, rf). If
the reset strings are not present, but
initialization strings
are, the initialization strings will
be output. Otherwise,
reset acts identically to init.
longname
If the terminfo database is present and an
entry for the user’s
terminal exists (see -Ttype above), then
the long name of the
terminal will be put out. The long
name is the last name in the
first line of the terminal’s
description in the terminfo
database [see term(5)].
If tput is invoked by a link named reset, this has the same effect
as
tput reset. See tset for comparison, which has similar
behavior.
EXAMPLES
tput init
Initialize the terminal according
to the type of terminal in the
environmental variable TERM.
This command should be included in
everyone’s .profile after the
environmental variable TERM has been
exported, as illustrated on
the profile(5) manual page.
tput -T5620 reset
Reset an AT&T 5620 terminal,
overriding the type of terminal in
the environmental variable
TERM.
tput cup 0 0
Send the sequence to move the cursor to
row 0, column 0 (the upper
left corner of the screen,
usually known as the "home" cursor
position).
tput clear
Echo the clear-screen sequence for the
current terminal.
tput cols
Print the number of columns for the current
terminal.
tput -T450 cols
Print the number of columns for the 450
terminal.
bold=.‘tput smso.‘ offbold=.‘@TPUT@ rmso.‘
Set the shell variables
bold, to begin stand-out mode sequence,
and offbold, to end
standout mode sequence, for the current termi-
nal. This might
be followed by a prompt: echo "${bold}Please type
in your name:
${offbold}\c"
tput hc
Set exit code to indicate if the current
terminal is a hard copy
terminal.
tput cup 23 4
Send the sequence to move the cursor to
row 23, column 4.
tput cup
Send the terminfo string for cursor-movement,
with no parameters
substituted.
tput longname
Print the long name from the terminfo
database for the type of
terminal specified in the environmental
variable TERM.
tput -S <<!
> clear
>
cup 10 10
> bold
> !
This example shows tput processing several capabilities in
one
invocation. It clears the screen, moves the cursor to
position
10, 10 and turns on bold (extra bright) mode. The list
is termi-
nated by an exclamation mark (!) on a line by
itself.
FILES
/usr/share/terminfo
compiled terminal
description database
/usr/share/tabset/*
tab settings for some
terminals, in a format appropriate to be
output to the terminal
(escape sequences that set margins and
tabs); for more
information, see the "Tabs and Initialization"
section of
terminfo(5)
EXIT CODES
If the -S option is used, tput checks for errors from
each line, and if
any errors are found, will set the exit code to 4
plus the number of
lines with errors. If no errors are found, the
exit code is 0. No
indication of which line failed can be given
so exit code 1 will never
appear. Exit codes 2, 3, and 4 retain their
usual interpretation. If
the -S option is not used, the exit code
depends on the type of cap-
name:
boolean
a value of 0 is set for TRUE and 1
for FALSE.
string a value of 0 is set if the capname is defined for this
ter-
minal type (the value of capname is returned on
standard
output); a value of 1 is set if capname is not
defined for
this terminal type (nothing is written to
standard output).
integer
a value of 0 is always set,
whether or not capname is
defined for this terminal
type. To determine if capname is
defined for this
terminal type, the user must test the
value written
to standard output. A value of -1 means that
capname is
not defined for this terminal type.
other reset or init may fail to find their respective files.
In
that case, the exit code is set to 4 + errno.
Any other exit code indicates an error; see the DIAGNOSTICS section.
DIAGNOSTICS
tput prints the following error messages and sets
the corresponding
exit codes.
exit code error
message
---------------------------------------------------------------------
0
(capname is a numeric variable that is not specified in
the terminfo(5) database for this terminal type, e.g.
tput -T450 lines and @TPUT@ -T2621 xmc)
1 no error
message is printed, see the EXIT CODES section.
2 usage
error
3 unknown terminal type or no terminfo database
4 unknown terminfo capability capname
>4
error occurred in
-S
---------------------------------------------------------------------
PORTABILITY
The longname and -S options, and the
parameter-substitution features
used in the cup example, are not
supported in BSD curses or in AT&T/USL
curses before SVr4.
X/Open documents only the operands for clear, init and reset. In
this
implementation, clear is part of the capname support. Other
implemen-
tations of tput on SVr4-based systems such as Solaris, IRIX64 and
HPUX
as well as others such as AIX and Tru64 provide support for
capname
operands. A few platforms such as FreeBSD and NetBSD
recognize termcap
names rather than terminfo capability names in
their respective tput
commands.
SEE ALSO
clear(1), stty(1), tabs(1), terminfo(5).
This describes ncurses version 5.7 (patch 20090207).
tput(1)