bash.1

android-w.song.android.widget

The number of
parameters to the current subroutine (shell function or script executed
with \fB.\fP or \fBsource\fP) is at the top of the stack.
When a subroutine is executed, the number of parameters passed is pushed onto
.SM
.BR BASH_ARGC .
The shell sets
.SM
.B BASH_ARGC
only when in extended debugging mode (see the description of the
.B extdebug
option to the
.B shopt
builtin below)
.TP
.B BASH_ARGV
An array variable containing all of the parameters in the current \fBbash\fP
execution call stack.  The final parameter of the last subroutine call
is at the top of the stack; the first parameter of the initial call is
at the bottom.  When a subroutine is executed, the parameters supplied
are pushed onto
.SM
.BR BASH_ARGV .
The shell sets
.SM
.B BASH_ARGV
only when in extended debugging mode
(see the description of the
.B extdebug
option to the
.B shopt
builtin below)
.TP
.B BASH_CMDS
An associative array variable whose members correspond to the internal
hash table of commands as maintained by the \fBhash\fP builtin.
Elements added to this array appear in the hash table; unsetting array
elements cause commands to be removed from the hash table.
.TP
.B BASH_COMMAND
The command currently being executed or about to be executed, unless the
shell is executing a command as the result of a trap,
in which case it is the command executing at the time of the trap.
.TP
.B BASH_EXECUTION_STRING
The command argument to the \fB\-c\fP invocation option.
.TP
.B BASH_LINENO
An array variable whose members are the line numbers in source files
where each corresponding member of
.SM
.B FUNCNAME
was invoked.
\fB${BASH_LINENO[\fP\fI$i\fP\fB]}\fP is the line number in the source
file (\fB${BASH_SOURCE[\fP\fI$i+1\fP\fB]}\fP) where
\fB${FUNCNAME[\fP\fI$i\fP\fB]}\fP was called
(or \fB${BASH_LINENO[\fP\fI$i-1\fP\fB]}\fP if referenced within another
shell function).
Use
.SM
.B LINENO
to obtain the current line number.
.TP
.B BASH_REMATCH
An array variable whose members are assigned by the \fB=~\fP binary
operator to the \fB[[\fP conditional command.
The element with index 0 is the portion of the string
matching the entire regular expression.
The element with index \fIn\fP is the portion of the
string matching the \fIn\fPth parenthesized subexpression.
This variable is read-only.
.TP
.B BASH_SOURCE
An array variable whose members are the source filenames
where the corresponding shell function names in the
.SM
.B FUNCNAME
array variable are defined.
The shell function
\fB${FUNCNAME[\fP\fI$i\fP\fB]}\fP is defined in the file
\fB${BASH_SOURCE[\fP\fI$i\fP\fB]}\fP and called from
\fB${BASH_SOURCE[\fP\fI$i+1\fP\fB]}\fP.
.TP
.B BASH_SUBSHELL
Incremented by one each time a subshell or subshell environment is spawned.
The initial value is 0.
.TP
.B BASH_VERSINFO
A readonly array variable whose members hold version information for
this instance of
.BR bash .
The values assigned to the array members are as follows:
.sp .5
.RS
.TP 24
.B BASH_VERSINFO[\fR0\fP]
The major version number (the \fIrelease\fP).
.TP
.B BASH_VERSINFO[\fR1\fP]
The minor version number (the \fIversion\fP).
.TP
.B BASH_VERSINFO[\fR2\fP]
The patch level.
.TP
.B BASH_VERSINFO[\fR3\fP]
The build version.
.TP
.B BASH_VERSINFO[\fR4\fP]
The release status (e.g., \fIbeta1\fP).
.TP
.B BASH_VERSINFO[\fR5\fP]
The value of
.SM
.BR MACHTYPE .
.RE
.TP
.B BASH_VERSION
Expands to a string describing the version of this instance of
.BR bash .
.TP
.B COMP_CWORD
An index into \fB${COMP_WORDS}\fP of the word containing the current
cursor position.
This variable is available only in shell functions invoked by the
programmable completion facilities (see \fBProgrammable Completion\fP
below).
.TP
.B COMP_KEY
The key (or final key of a key sequence) used to invoke the current
completion function.
.TP
.B COMP_LINE
The current command line.
This variable is available only in shell functions and external
commands invoked by the
programmable completion facilities (see \fBProgrammable Completion\fP
below).
.TP
.B COMP_POINT
The index of the current cursor position relative to the beginning of
the current command.
If the current cursor position is at the end of the current command,
the value of this variable is equal to \fB${#COMP_LINE}\fP.
This variable is available only in shell functions and external
commands invoked by the
programmable completion facilities (see \fBProgrammable Completion\fP
below).
.TP
.B COMP_TYPE
Set to an integer value corresponding to the type of completion attempted
that caused a completion function to be called:
\fITAB\fP, for normal completion,
\fI?\fP, for listing completions after successive tabs,
\fI!\fP, for listing alternatives on partial word completion,
\fI@\fP, to list completions if the word is not unmodified,
or
\fI%\fP, for menu completion.
This variable is available only in shell functions and external
commands invoked by the
programmable completion facilities (see \fBProgrammable Completion\fP
below).
.TP
.B COMP_WORDBREAKS
The set of characters that the \fBreadline\fP library treats as word
separators when performing word completion.
If
.SM
.B COMP_WORDBREAKS
is unset, it loses its special properties, even if it is
subsequently reset.
.TP
.B COMP_WORDS
An array variable (see \fBArrays\fP below) consisting of the individual
words in the current command line.
The line is split into words as \fBreadline\fP would split it, using
.SM
.B COMP_WORDBREAKS
as described above.
This variable is available only in shell functions invoked by the
programmable completion facilities (see \fBProgrammable Completion\fP
below).
.TP
.B COPROC
An array variable (see \fBArrays\fP below) created to hold the file descriptors
for output from and input to an unnamed coprocess (see \fBCoprocesses\fP
above).
.TP
.B DIRSTACK
An array variable (see
.B Arrays
below) containing the current contents of the directory stack.
Directories appear in the stack in the order they are displayed by the
.B dirs
builtin.
Assigning to members of this array variable may be used to modify
directories already in the stack, but the
.B pushd
and
.B popd
builtins must be used to add and remove directories.
Assignment to this variable will not change the current directory.
If
.SM
.B DIRSTACK
is unset, it loses its special properties, even if it is
subsequently reset.
.TP
.B EUID
Expands to the effective user ID of the current user, initialized at
shell startup.  This variable is readonly.
.TP
.B FUNCNAME
An array variable containing the names of all shell functions
currently in the execution call stack.
The element with index 0 is the name of any currently-executing
shell function.
The bottom-most element (the one with the highest index) is
.if t \f(CW"main"\fP.
.if n "main".
This variable exists only when a shell function is executing.
Assignments to
.SM
.B FUNCNAME
have no effect and return an error status.
If
.SM
.B FUNCNAME
is unset, it loses its special properties, even if it is
subsequently reset.
.if t .sp 0.5
.if n .sp 1
This variable can be used with \fBBASH_LINENO\fP and \fBBASH_SOURCE\fP.
Each element of \fBFUNCNAME\fP has corresponding elements in
\fBBASH_LINENO\fP and \fBBASH_SOURCE\fP to describe the call stack.
For instance, \fB${FUNCNAME[\fP\fI$i\fP\fB]}\fP was called from the file
\fB${BASH_SOURCE[\fP\fI$i+1\fP\fB]}\fP at line number
\fB${BASH_LINENO[\fP\fI$i\fP\fB]}\fP.
The \fBcaller\fP builtin displays the current call stack using this
information.
.TP
.B GROUPS
An array variable containing the list of groups of which the current
user is a member.
Assignments to    
.SM
.B GROUPS
have no effect and return an error status.
If
.SM
.B GROUPS
is unset, it loses its special properties, even if it is
subsequently reset.
.TP
.B HISTCMD
The history number, or index in the history list, of the current
command.
If
.SM
.B HISTCMD
is unset, it loses its special properties, even if it is
subsequently reset.
.TP
.B HOSTNAME
Automatically set to the name of the current host.
.TP
.B HOSTTYPE
Automatically set to a string that uniquely
describes the type of machine on which
.B bash
is executing.
The default is system-dependent.
.TP
.B LINENO
Each time this parameter is referenced, the shell substitutes
a decimal number representing the current sequential line number
(starting with 1) within a script or function.  When not in a
script or function, the value substituted is not guaranteed to
be meaningful.
If
.SM
.B LINENO
is unset, it loses its special properties, even if it is
subsequently reset.
.TP
.B MACHTYPE
Automatically set to a string that fully describes the system
type on which
.B bash
is executing, in the standard GNU \fIcpu-company-system\fP format.
The default is system-dependent.
.TP
.B MAPFILE
An array variable (see \fBArrays\fP below) created to hold the text
read by the \fBmapfile\fP builtin when no variable name is supplied.
.TP
.B OLDPWD
The previous working directory as set by the
.B cd
command.
.TP
.B OPTARG
The value of the last option argument processed by the
.B getopts
builtin command (see
.SM
.B SHELL BUILTIN COMMANDS
below).
.TP
.B OPTIND
The index of the next argument to be processed by the
.B getopts
builtin command (see
.SM
.B SHELL BUILTIN COMMANDS
below).
.TP
.B OSTYPE
Automatically set to a string that
describes the operating system on which
.B bash
is executing.
The default is system-dependent.
.TP
.B PIPESTATUS
An array variable (see
.B Arrays
below) containing a list of exit status values from the processes
in the most-recently-executed foreground pipeline (which may
contain only a single command).
.TP
.B PPID
The process ID of the shell's parent.  This variable is readonly.
.TP
.B PWD
The current working directory as set by the
.B cd
command.
.TP
.B RANDOM
Each time this parameter is referenced, a random integer between
0 and 32767 is
generated.  The sequence of random numbers may be initialized by assigning
a value to
.SM
.BR RANDOM .
If
.SM
.B RANDOM
is unset, it loses its special properties, even if it is
subsequently reset.
.TP
.B READLINE_LINE
The contents of the
.B readline
line buffer, for use with
.if t \f(CWbind -x\fP
.if n "bind -x"
(see
.SM
.B "SHELL BUILTIN COMMANDS"
below).
.TP
.B READLINE_POINT
The position of the insertion point in the
.B readline
line buffer, for use with
.if t \f(CWbind -x\fP
.if n "bind -x"
(see
.SM
.B "SHELL BUILTIN COMMANDS"
below).
.TP
.B REPLY
Set to the line of input read by the
.B read
builtin command when no arguments are supplied.
.TP
.B SECONDS
Each time this parameter is
referenced, the number of seconds since shell invocation is returned.  If a
value is assigned to 
.SM
.BR SECONDS ,
the value returned upon subsequent
references is
the number of seconds since the assignment plus the value assigned.
If
.SM
.B SECONDS
is unset, it loses its special properties, even if it is
subsequently reset.
.TP
.B SHELLOPTS
A colon-separated list of enabled shell options.  Each word in
the list is a valid argument for the
.B \-o
option to the
.B set
builtin command (see
.SM
.B "SHELL BUILTIN COMMANDS"
below).  The options appearing in
.SM
.B SHELLOPTS
are those reported as
.I on
by \fBset \-o\fP.
If this variable is in the environment when
.B bash
starts up, each shell option in the list will be enabled before
reading any startup files.
This variable is read-only.
.TP
.B SHLVL
Incremented by one each time an instance of
.B bash
is started.
.TP
.B UID
Expands to the user ID of the current user, initialized at shell startup.
This variable is readonly.
.PD
.PP
The following variables are used by the shell.  In some cases,
.B bash
assigns a default value to a variable; these cases are noted
below.
.PP
.PD 0
.TP
.B BASH_ENV
If this parameter is set when \fBbash\fP is executing a shell script,
its value is interpreted as a filename containing commands to
initialize the shell, as in
.IR ~/.bashrc .
The value of
.SM
.B BASH_ENV
is subjected to parameter expansion, command substitution, and arithmetic
expansion before being interpreted as a file name.
.SM
.B PATH
is not used to search for the resultant file name.
.TP
.B BASH_XTRACEFD
If set to an integer corresponding to a valid file descriptor, \fBbash\fP
will write the trace output generated when
.if t \f(CWset -x\fP
.if n \fIset -x\fP
is enabled to that file descriptor.
The file descriptor is closed when
.SM
.B BASH_XTRACEFD
is unset or assigned a new value.
Unsetting
.SM
.B BASH_XTRACEFD
or assigning it the empty string causes the
trace output to be sent to the standard error.
Note that setting