TERMCAP(3)

NAME
tgetent, tgetnum, tgetflag, tgetstr, tgoto, tputs - terminal independent operation routines

LIBRARY
libtermcap

SYNOPSIS
#include <termcap.h>
char PC;
char *BC;
char *UP;
short ospeed;
struct tinfo *info;
int
tgetent(char *bp, char *name);
int
tgetnum(char *id);
int
tgetflag(char *id);
char *
tgetstr(char *id, char **area);
char *
tgoto(char *cm, int destcol, int destline);
void
tputs(char *cp, int affcnt, int (*outc)(int));
int
t_getent(struct tinfo **info, char *name);
int
t_getnum(struct tinfo *info, char *id);
int
t_getflag(struct tinfo *info, char *id);
char *
t_getstr(struct tinfo *info, char *id, char **area, size_t *limit);
char *
t_agetstr(struct tinfo *info, char *id, char **buffer, char **area);
int
t_getterm(struct tinfo *info, char **area, size_t *limit);
int
t_goto(struct tinfo *info, char *id, int destcol, int destline, char *buffer, size_t limit);
int
t_puts(struct tinfo *info, char *cp, int affcnt, void (*outc)(char, void *), void *args);
void
t_freent(char *info);
int
t_setinfo(struct tinfo **info, const char *entry);

DESCRIPTION
These functions extract and use capabilities from a terminal capability data base, usually /usr/share/misc/termcap, the format of which is described in termcap(5). These are low level routines; see curses(3) for a higher level package.

The tgetent() function extracts the entry for terminal name into the buffer at bp. The bp argument should be a character buffer of size 1024 and must be retained through all subsequent calls to tgetnum(), tgetflag(), and tgetstr(). The tgetent() function returns -1 if none of the termcap data base files could be opened, 0 if the terminal name given does not have an entry, and 1 if all goes well. It will look in the environment for a TERMCAP variable. If found, and the value does not begin with a slash, the value does not contain the ZZ capability (see NOTES for a description of this capability), and the terminal type name is the same as the environment string TERM, the TERMCAP string is used instead of reading a termcap file. If the value does contain the ZZ capability then the TERM environment string is used to read termcap, if the read fails for any reason the value of TERMCAP will be used despite it containing ZZ. If TERMCAP does begin with a slash, the string is used as a path name of the termcap file to search. If TERMCAP does not begin with a slash and name is different from TERM, tgetent() searches the files $HOME/.termcap and /usr/share/misc/termcap, in that order, unless the environment variable TERMPATH exists, in which case it specifies a list of file pathnames (separated by spaces or colons) to be searched instead. Whenever multiple files are searched and a tc field occurs in the requested entry, the entry it names must be found in the same file or one of the succeeding files. This can speed up entry into programs that call tgetent(), as well as help debug new terminal descriptions or make one for your terminal if you can't write the file /usr/share/misc/termcap.

The tgetnum() function gets the numeric value of capability id, returning -1 if it is not given for the terminal. The tgetflag() function returns 1 if the specified capability is present in the terminal's entry, 0 if it is not. The tgetstr() function returns the string value of the capability id, places it in the buffer at area, and advances the area pointer. It decodes the abbreviations for this field described in termcap(5), except for cursor addressing and padding information. The tgetstr() function returns NULL if the capability was not found.

The tgoto() function returns a cursor addressing string decoded from cm to go to column destcol in line destline. It uses the external variables UP (from the up capability) and BC (if bc is given rather than bs) if necessary to avoid placing \n, ^D or ^@ in the returned string. (Programs which call tgoto() should be sure to turn off the XTABS bit(s), since tgoto() may now output a tab. Note that programs using termcap should in general turn off XTABS anyway since some terminals use control-I for other functions, such as nondestructive space.) If a % sequence is given which is not understood, then tgoto() returns (OOPS).

The tputs() function decodes the leading padding information of the string cp; affcnt gives the number of lines affected by the operation, or 1 if this is not applicable, outc is a routine which is called with each character in turn. The external variable ospeed should contain the output speed of the terminal as encoded by stty(3). The external variable PC should contain a pad character to be used (from the pc capability) if a null (^@) is inappropriate.

The t_getent() function operates in a similar manner to the tgetent() function excepting that the info argument is a pointer to a pointer of the opaque type tinfo. If the call to t_getent() succeeds then the argument info will be updated with the address of an object that contains the termcap entry. This pointer can then be passed to calls of t_getnum(), t_getflag() and t_getstr(). When the information pointed to by info is no longer required any storage associated with the object can be released by calling t_freent().

The functions t_getnum() and t_getflag() operate in the same manner as tgetnum() and tgetflag() with the exception that the pointer to the termcap object is passed along with the id of the capability required.

The function t_getstr() performs the same function as tgetstr() but has a limit parameter that gives the number of characters that can be inserted in to the array pointed to by area. The limit argument is updated by the t_getstr() call to give the number of characters that remain available in area. If the t_getstr call fails then NULL will be returned and errno set to indicate the failure, ENOENT indicates there was no termcap entry for the given id, E2BIG indicates the retrieved entry would have overflowed area. If t_getstr is called with area being NULL then the size required to hold the capability string will be returned in limit so the caller can allocate enough storage to hold the capability.

The function t_agetstr() performs the same function as t_getstr() except sufficient memory is first allocated to hold the desired string argument before adding it to the buffer. To initialise the buffer for t_agetstr() the first call must be done with the contents of buffer set to NULL. Subsequent calls to t_agetstr() can pass buffer and area in unmodified and the requested string argument will be appended to the buffer after sufficient memory has been allocated. Modifying either buffer or area between calls to t_agetstr() will certainly lead to the function misbehaving. When the storage allocated by t_agetstr() is no longer required it can be freed by passing the pointer contained in buffer to free(). If an error occurs within t_agetstr() a NULL will be returned and buffer and area will remain unmodified. NOTE t_agetstr() uses realloc() to reallocate the buffer memory so saving a copy of either buffer or area for use after subsequent calls to t_agetstr() is likely to fail. It is best to keep offsets from buffer to the desired string and calculate pointer addresses only after all the calls to t_agetstr() have been done.

The function t_getterm() returns a copy of the termcap name string of the termcap entry associated with info in the buffer pointed to by area. t_getterm() returns 0 on success and -1 on error. On error errno will be set to EINVAL if the termcap entry in info is malformed or E2BIG if the size of the name exceeds the size specified by limit. If area is NULL then the size required to hold the terminal name will be returned in limit allowing sufficient storage to be allocated. If limit is NULL then no bounds checking will be performed.

The t_goto() function is the same as the tgoto() function excepting that the capabilities for up and bc are extracted from the info object and that the string formed by t_goto() is placed in the buffer argument, the number of characters allowed to be placed in buffer is controlled by limit. If the expansion performed by t_goto() would exceed the space in buffer then t_goto() will return -1 and set errno to E2BIG. The function t_puts() is similar to the tputs() function excepting that info holds a pointer to the termcap object that was returned by a previous t_getent() call, this object will be used to retrieve the pc attribute for the terminal. The outc function is a pointer to a function that will be called by t_puts() to output each character in the cp string. The outc function will be called with two parameters. The first is the character to be printed and the second is an optional argument that was passed to t_puts() in the args argument. The interpretation of the contents of args is dependent soley on the implementation of outc.

The t_setinfo() function allows the termcap entry contained in the entry string to be inserted into the the info structure. Memory sufficient to hold the contents of entry is automatically allocated. This allows the programmer to provide a fail over terminal capability string if fetching the termcap entry from the termcap database fails. The format of the string entry is assumed to be a valid termcap entry.

NOTE: A special capability of ZZ is added to the end of the termcap entry retrieved. The number that follows this entry is the address of the buffer allocated to hold the full termcap entry. The caller may retrieve the pointer to the extended buffer by performing a tgetstr() to retrieve the ZZ capability, the string is the output of a printf() %p and may be converted back to a pointer using sscanf() or similar. The ZZ capability is only necessary if the caller wishes to directly manipulate the termcap entry, all the termcap function calls automatically use the extended buffer to retrieve terminal capabilities.

FILES
/usr/lib/libtermcap.a
    -l termcap library (also known as -l termlib)
/usr/share/misc/termcap
    standard terminal capability data base
$HOME/.termcap
    user's terminal capability data base

SEE ALSO
ex(1), curses(3), termcap(5)

HISTORY
The termcap functions appeared in 4.0BSD.