path: root/doc/while.n

'\"
'\" Copyright (c) 1993 The Regents of the University of California.
'\" Copyright (c) 1994-1997 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: while.n,v 1.3.18.1 2004/10/27 14:43:15 dkf Exp $
'\" 
.so man.macros
.TH while n "" Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
while \- Execute script repeatedly as long as a condition is met
.SH SYNOPSIS
\fBwhile \fItest body\fR
.BE

.SH DESCRIPTION
.PP
The \fBwhile\fR command evaluates \fItest\fR as an expression
(in the same way that \fBexpr\fR evaluates its argument).
The value of the expression must a proper boolean
value; if it is a true value
then \fIbody\fR is executed by passing it to the Tcl interpreter.
Once \fIbody\fR has been executed then \fItest\fR is evaluated
again, and the process repeats until eventually \fItest\fR
evaluates to a false boolean value.  \fBContinue\fR
commands may be executed inside \fIbody\fR to terminate the current
iteration of the loop, and \fBbreak\fR
commands may be executed inside \fIbody\fR to cause immediate
termination of the \fBwhile\fR command.  The \fBwhile\fR command
always returns an empty string.
.PP
Note: \fItest\fR should almost always be enclosed in braces.  If not,
variable substitutions will be made before the \fBwhile\fR
command starts executing, which means that variable changes
made by the loop body will not be considered in the expression.
This is likely to result in an infinite loop.  If \fItest\fR is">= 0000010
INPCK = 0000020
ISTRIP = 0000040
INLCR = 0000100
IGNCR = 0000200
ICRNL = 0000400
IUCLC = 0001000
IXON = 0002000
IXANY = 0004000
IXOFF = 0010000
IMAXBEL = 0020000
IBLKMD = 0040000
OPOST = 0000001
OLCUC = 0000002
ONLCR = 0000004
OCRNL = 0000010
ONOCR = 0000020
ONLRET = 0000040
OFILL = 0000100
OFDEL = 0000200
NLDLY = 0000400
NL0 = 0
NL1 = 0000400
CRDLY = 0003000
CR0 = 0
CR1 = 0001000
CR2 = 0002000
CR3 = 0003000
TABDLY = 0014000
TAB0 = 0
TAB1 = 0004000
TAB2 = 0010000
TAB3 = 0014000
XTABS = 0014000
BSDLY = 0020000
BS0 = 0
BS1 = 0020000
VTDLY = 0040000
VT0 = 0
VT1 = 0040000
FFDLY = 0100000
FF0 = 0
FF1 = 0100000
PAGEOUT = 0200000
WRAP = 0400000
CBAUD = 000000017
CSIZE = 000000060
CS5 = 0
CS6 = 000000020
CS7 = 000000040
CS8 = 000000060
CSTOPB = 000000100
CREAD = 000000200
PARENB = 000000400
PARODD = 000001000
HUPCL = 000002000
CLOCAL = 000004000
RCV1EN = 000010000
XMT1EN = 000020000
LOBLK = 000040000
XCLUDE = 000100000
CIBAUD = 003600000
PAREXT = 004000000
CNEW_RTSCTS = 010000000
ISIG = 0000001
ICANON = 0000002
XCASE = 0000004
ECHO = 0000010
ECHOE = 0000020
ECHOK = 0000040
ECHONL = 0000100
NOFLSH = 0000200
IEXTEN = 0000400
ITOSTOP = 0100000
TOSTOP = ITOSTOP
ECHOCTL = 0001000
ECHOPRT = 0002000
ECHOKE = 0004000
DEFECHO = 0010000
FLUSHO = 0020000
PENDIN = 0040000
TIOC = (ord('T')<<8)
TCGETA = (TIOC|1)
TCSETA = (TIOC|2)
TCSETAW = (TIOC|3)
TCSETAF = (TIOC|4)
TCSBRK = (TIOC|5)
TCXONC = (TIOC|6)
TCFLSH = (TIOC|7)
LDISC0 = 0
LDISC1 = 1
NTTYDISC = LDISC1
TIOCFLUSH = (TIOC|12)
TCSETLABEL = (TIOC|31)
TCDSET = (TIOC|32)
TCBLKMD = (TIOC|33)
TIOCPKT = (TIOC|112)
TIOCPKT_DATA = 0x00
TIOCPKT_FLUSHREAD = 0x01
TIOCPKT_FLUSHWRITE = 0x02
TIOCPKT_NOSTOP = 0x10
TIOCPKT_DOSTOP = 0x20
TIOCPKT_IOCTL = 0x40
TIOCNOTTY = (TIOC|113)
TIOCSTI = (TIOC|114)
TFIOC = (ord('F')<<8)
oFIONREAD = (TFIOC|127)
TO_STOP = LOBLK
IOCTYPE = 0xff00
TCGETS = (TIOC|13)
TCSETS = (TIOC|14)
TCSETSW = (TIOC|15)
TCSETSF = (TIOC|16)
TCSANOW = ((ord('T')<<8)|14)
TCSADRAIN = ((ord('T')<<8)|15)
TCSAFLUSH = ((ord('T')<<8)|16)
TCIFLUSH = 0
TCOFLUSH = 1
TCIOFLUSH = 2
TCOOFF = 0
TCOON = 1
TCIOFF = 2
TCION = 3
tIOC = (ord('t')<<8)
TIOCGETD = (tIOC|0)
TIOCSETD = (tIOC|1)
TIOCHPCL = (tIOC|2)
TIOCGETP = (tIOC|8)
TIOCSETP = (tIOC|9)
TIOCSETN = (tIOC|10)
TIOCEXCL = (tIOC|13)
TIOCNXCL = (tIOC|14)
TIOCSETC = (tIOC|17)
TIOCGETC = (tIOC|18)
TIOCLBIS = (tIOC|127)
TIOCLBIC = (tIOC|126)
TIOCLSET = (tIOC|125)
TIOCLGET = (tIOC|124)
TIOCSBRK = (tIOC|123)
TIOCCBRK = (tIOC|122)
TIOCSDTR = (tIOC|121)
TIOCCDTR = (tIOC|120)
TIOCSLTC = (tIOC|117)
TIOCGLTC = (tIOC|116)
TIOCOUTQ = (tIOC|115)
TIOCSTOP = (tIOC|111)
TIOCSTART = (tIOC|110)
TIOCGSID = (tIOC|22)
TIOCSSID = (tIOC|24)
TIOCMSET = (tIOC|26)
TIOCMBIS = (tIOC|27)
TIOCMBIC = (tIOC|28)
TIOCMGET = (tIOC|29)
TIOCM_LE = 0001
TIOCM_DTR = 0002
TIOCM_RTS = 0004
TIOCM_ST = 0010
TIOCM_SR = 0020
TIOCM_CTS = 0040
TIOCM_CAR = 0100
TIOCM_CD = TIOCM_CAR
TIOCM_RNG = 0200
TIOCM_RI = TIOCM_RNG
TIOCM_DSR = 0400
TIOCREMOTE = (tIOC|30)
TIOCSIGNAL = (tIOC|31)
ISPTM = ((ord('P')<<8)|1)
UNLKPT = ((ord('P')<<8)|2)
SVR4SOPEN = ((ord('P')<<8)|100)
LDIOC = (ord('D')<<8)
LDOPEN = (LDIOC|0)
LDCLOSE = (LDIOC|1)
LDCHG = (LDIOC|2)
LDGETT = (LDIOC|8)
LDSETT = (LDIOC|9)
LDSMAP = (LDIOC|10)
LDGMAP = (LDIOC|11)
LDNMAP = (LDIOC|12)
DIOC = (ord('d')<<8)
DIOCGETP = (DIOC|8)
DIOCSETP = (DIOC|9)
FIORDCHK = ((ord('f')<<8)|3)
CLNEXT = CTRL(ord('v'))
CWERASE = CTRL(ord('w'))
CFLUSHO = CTRL(ord('o'))
CFLUSH = CFLUSHO
CRPRNT = CTRL(ord('r'))
CDSUSP = CTRL(ord('y'))
SSPEED = B9600
TERM_NONE = 0
TERM_TEC = 1
TERM_V61 = 2
TERM_V10 = 3
TERM_TEX = 4
TERM_D40 = 5
TERM_H45 = 6
TERM_D42 = 7
TM_NONE = 0000
TM_SNL = 0001
TM_ANL = 0002
TM_LCF = 0004
TM_CECHO = 0010
TM_CINVIS = 0020
TM_SET = 0200
LDISC0 = 0
LDISC1 = 1
NTTYDISC = LDISC1
TIOCFLUSH = (TIOC|12)
TCSETLABEL = (TIOC|31)
TCDSET = (TIOC|32)
TCBLKMD = (TIOC|33)
TIOCPKT = (TIOC|112)
TIOCPKT_DATA = 0x00
TIOCPKT_FLUSHREAD = 0x01
TIOCPKT_FLUSHWRITE = 0x02
TIOCPKT_NOSTOP = 0x10
TIOCPKT_DOSTOP = 0x20
TIOCPKT_IOCTL = 0x40
TIOCNOTTY = (TIOC|113)
TIOCSTI = (TIOC|114)
TFIOC = (ord('F')<<8)
oFIONREAD = (TFIOC|127)
TO_STOP = LOBLK
IOCTYPE = 0xff00
TCGETS = (TIOC|13)
TCSETS = (TIOC|14)
TCSETSW = (TIOC|15)
TCSETSF = (TIOC|16)
TCSANOW = ((ord('T')<<8)|14)
TCSADRAIN = ((ord('T')<<8)|15)
TCSAFLUSH = ((ord('T')<<8)|16)
TCIFLUSH = 0
TCOFLUSH = 1
TCIOFLUSH = 2
TCOOFF = 0
TCOON = 1
TCIOFF = 2
TCION = 3
tIOC = (ord('t')<<8)
TIOCGETD = (tIOC|0)
TIOCSETD = (tIOC|1)
TIOCHPCL = (tIOC|2)
TIOCGETP = (tIOC|8)
TIOCSETP = (tIOC|9)
TIOCSETN = (tIOC|10)
TIOCEXCL = (tIOC|13)
TIOCNXCL = (tIOC|14)
TIOCSETC = (tIOC|17)
TIOCGETC = (tIOC|18)
TIOCLBIS = (tIOC|127)
TIOCLBIC = (tIOC|126)
TIOCLSET = (tIOC|125)
TIOCLGET = (tIOC|124)
TIOCSBRK = (tIOC|123)
TIOCCBRK = (tIOC|122)
TIOCSDTR = (tIOC|121)
TIOCCDTR = (tIOC|120)
TIOCSLTC = (tIOC|117)
TIOCGLTC = (tIOC|116)
TIOCOUTQ = (tIOC|115)
TIOCSTOP = (tIOC|111)
TIOCSTART = (tIOC|110)
TIOCGSID = (tIOC|22)
TIOCSSID = (tIOC|24)
TIOCMSET = (tIOC|26)
TIOCMBIS = (tIOC|27)
TIOCMBIC = (tIOC|28)
TIOCMGET = (tIOC|29)
TIOCM_LE = 0001
TIOCM_DTR = 0002
TIOCM_RTS = 0004
TIOCM_ST = 0010
TIOCM_SR = 0020
TIOCM_CTS = 0040
TIOCM_CAR = 0100
TIOCM_CD = TIOCM_CAR
TIOCM_RNG = 0200
TIOCM_RI = TIOCM_RNG
TIOCM_DSR = 0400
TIOCREMOTE = (tIOC|30)
TIOCSIGNAL = (tIOC|31)
ISPTM = ((ord('P')<<8)|1)
UNLKPT = ((ord('P')<<8)|2)
SVR4SOPEN = ((ord('P')<<8)|100)
LDIOC = (ord('D')<<8)
LDOPEN = (LDIOC|0)
LDCLOSE = (LDIOC|1)
LDCHG = (LDIOC|2)
LDGETT = (LDIOC|8)
LDSETT = (LDIOC|9)
LDSMAP = (LDIOC|10)
LDGMAP = (LDIOC|11)
LDNMAP = (LDIOC|12)
DIOC = (ord('d')<<8)
DIOCGETP = (DIOC|8)
DIOCSETP = (DIOC|9)
FIORDCHK = ((ord('f')<<8)|3)