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tclvars.n
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1995-07-25
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199 lines
ttttccccllllvvvvaaaarrrrssss((((nnnn)))) TTTTccccllll (((( )))) ttttccccllllvvvvaaaarrrrssss((((nnnn))))
_________________________________________________________________
NNNNAAAAMMMMEEEE
tclvars - Variables used by Tcl
_________________________________________________________________
DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
The following global variables are created and managed
automatically by the Tcl library. Except where noted below,
these variables should normally be treated as read-only by
application-specific code and by users.
eeeennnnvvvv
This variable is maintained by Tcl as an array whose
elements are the environment variables for the process.
Reading an element will return the value of the
corresponding environment variable. Setting an element
of the array will modify the corresponding environment
variable or create a new one if it doesn't already
exist. Unsetting an element of eeeennnnvvvv will remove the
corresponding environment variable. Changes to the eeeennnnvvvv
array will affect the environment passed to children by
commands like eeeexxxxeeeecccc. If the entire eeeennnnvvvv array is unset
then Tcl will stop monitoring eeeennnnvvvv accesses and will not
update environment variables.
eeeerrrrrrrroooorrrrCCCCooooddddeeee
After an error has occurred, this variable will be set
to hold additional information about the error in a
form that is easy to process with programs. eeeerrrrrrrroooorrrrCCCCooooddddeeee
consists of a Tcl list with one or more elements. The
first element of the list identifies a general class of
errors, and determines the format of the rest of the
list. The following formats for eeeerrrrrrrroooorrrrCCCCooooddddeeee are used by
the Tcl core; individual applications may define
additional formats.
AAAARRRRIIIITTTTHHHH _c_o_d_e _m_s_g
This format is used when an arithmetic error |
occurs (e.g. an attempt to divide by zero in the |
eeeexxxxpppprrrr command). _C_o_d_e identifies the precise error |
and _m_s_g provides a human-readable description of |
the error. _C_o_d_e will be either DIVZERO (for an |
attempt to divide by zero), DOMAIN (if an argument |
is outside the domain of a function, such as |
acos(-3)), IOVERFLOW (for integer overflow), |
OVERLFLOW (for a floating-point overflow), or |
UNKNOWN (if the cause of the error cannot be |
determined).
CCCCHHHHIIIILLLLDDDDKKKKIIIILLLLLLLLEEEEDDDD _p_i_d _s_i_g_N_a_m_e _m_s_g
Page 1 (printed 7/17/95)
ttttccccllllvvvvaaaarrrrssss((((nnnn)))) TTTTccccllll (((( )))) ttttccccllllvvvvaaaarrrrssss((((nnnn))))
This format is used when a child process has been
killed because of a signal. The second element of
eeeerrrrrrrroooorrrrCCCCooooddddeeee will be the process's identifier (in
decimal). The third element will be the symbolic
name of the signal that caused the process to
terminate; it will be one of the names from the
include file signal.h, such as SSSSIIIIGGGGPPPPIIIIPPPPEEEE. The
fourth element will be a short human-readable
message describing the signal, such as ``write on
pipe with no readers'' for SSSSIIIIGGGGPPPPIIIIPPPPEEEE.
CCCCHHHHIIIILLLLDDDDSSSSTTTTAAAATTTTUUUUSSSS _p_i_d _c_o_d_e
This format is used when a child process has
exited with a non-zero exit status. The second
element of eeeerrrrrrrroooorrrrCCCCooooddddeeee will be the process's
identifier (in decimal) and the third element will
be the exit code returned by the process (also in
decimal).
CCCCHHHHIIIILLLLDDDDSSSSUUUUSSSSPPPP _p_i_d _s_i_g_N_a_m_e _m_s_g
This format is used when a child process has been
suspended because of a signal. The second element
of eeeerrrrrrrroooorrrrCCCCooooddddeeee will be the process's identifier, in
decimal. The third element will be the symbolic
name of the signal that caused the process to
suspend; this will be one of the names from the
include file signal.h, such as SSSSIIIIGGGGTTTTTTTTIIIINNNN. The
fourth element will be a short human-readable
message describing the signal, such as
``background tty read'' for SSSSIIIIGGGGTTTTTTTTIIIINNNN.
NNNNOOOONNNNEEEE
This format is used for errors where no additional
information is available for an error besides the
message returned with the error. In these cases
eeeerrrrrrrroooorrrrCCCCooooddddeeee will consist of a list containing a
single element whose contents are NNNNOOOONNNNEEEE.
PPPPOOOOSSSSIIIIXXXX _e_r_r_N_a_m_e _m_s_g
If the first element of eeeerrrrrrrroooorrrrCCCCooooddddeeee is PPPPOOOOSSSSIIIIXXXX, then |
the error occurred during a POSIX kernel call.
The second element of the list will contain the
symbolic name of the error that occurred, such as
EEEENNNNOOOOEEEENNNNTTTT; this will be one of the values defined in
the include file errno.h. The third element of
the list will be a human-readable message
corresponding to _e_r_r_N_a_m_e, such as ``no such file
or directory'' for the EEEENNNNOOOOEEEENNNNTTTT case.
To set eeeerrrrrrrroooorrrrCCCCooooddddeeee, applications should use library
procedures such as TTTTccccllll____SSSSeeeettttEEEErrrrrrrroooorrrrCCCCooooddddeeee and TTTTccccllll____PPPPoooossssiiiixxxxEEEErrrrrrrroooorrrr, |
or they may invoke the eeeerrrrrrrroooorrrr command. If one of these
Page 2 (printed 7/17/95)
ttttccccllllvvvvaaaarrrrssss((((nnnn)))) TTTTccccllll (((( )))) ttttccccllllvvvvaaaarrrrssss((((nnnn))))
methods hasn't been used, then the Tcl interpreter will
reset the variable to NNNNOOOONNNNEEEE after the next error.
eeeerrrrrrrroooorrrrIIIInnnnffffoooo
After an error has occurred, this string will contain
one or more lines identifying the Tcl commands and
procedures that were being executed when the most
recent error occurred. Its contents take the form of a
stack trace showing the various nested Tcl commands
that had been invoked at the time of the error.
ttttccccllll____pppprrrreeeecccciiiissssiiiioooonnnn
If this variable is set, it must contain a decimal |
number giving the number of significant digits to |
include when converting floating-point values to |
strings. If this variable is not set then 6 digits are |
included. 17 digits is ``perfect'' for IEEE floating- |
point in that it allows double-precision values to be |
converted to strings and back to binary with no loss of |
precision.
KKKKEEEEYYYYWWWWOOOORRRRDDDDSSSS
arithmetic, error, environment, POSIX, precision,
subprocess, variables
Page 3 (printed 7/17/95)