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RWARRAY(3am) GNU Awk Extension Modules RWARRAY(3am)
NAME
writea, reada, writeall, readall - write and read gawk arrays to/from
files
SYNOPSIS
@load "rwarray"
ret = writea(file, array)
ret = reada(file, array)
ret = writeall(file)
ret = readall(file)
DESCRIPTION
The rwarray extension adds functions named writea(), reada(),
writeall(), and readall(), as follows.
writea()
This function takes a string argument, which is the name of the
file to which dump the array, and the array itself as the second
argument. writea() understands multidimensional arrays. It
returns one on success, or zero upon failure.
reada()
is the inverse of writea(); it reads the file named as its first
argument, filling in the array named as the second argument. It
clears the array first. Here too, the return value is one on
success and zero upon failure.
writeall()
This function takes a string argument, which is the name of the
file to which dump the state of all variables. Calling this
function is completely equivalent to calling writea() with the
second argument equal to SYMTAB. It returns one on success, or
zero upon failure.
readall()
This function takes a string argument, which is the name of the
file from which to read the contents of various global
variables. For each variable in the file, the data is loaded
unless the variable already exists. If the variable already
exists, the data for that variable in the file is ignored. It
returns one on success, or zero upon failure.
NOTES
The array created by reada() is identical to that written by writea()
in the sense that the contents are the same. However, due to
implementation issues, the array traversal order of the recreated array
will likely be different from that of the original array. As array
traversal order in AWK is by default undefined, this is not
(technically) a problem. If you need to guarantee a particular
traversal order, use the array sorting features in gawk to do so.
The file contains binary data. All integral values are written in
network byte order. However, double precision floating-point values
are written as native binary data. Thus, arrays containing only string
data can theoretically be dumped on systems with one byte order and
restored on systems with a different one, but this has not been tried.
EXAMPLE
@load "rwarray"
...
ret = writea("arraydump.bin", array)
...
ret = reada("arraydump.bin", array)
...
ret = writeall("globalstate.bin")
...
ret = readall("globalstate.bin")
SEE ALSO
GAWK: Effective AWK Programming, filefuncs(3am), fnmatch(3am),
fork(3am), inplace(3am), ordchr(3am), readdir(3am), readfile(3am),
revoutput(3am), time(3am).
AUTHOR
Arnold Robbins, arnold@skeeve.com.
COPYING PERMISSIONS
Copyright (C) 2012, 2013, 2018, 2022 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of this
manual page provided the copyright notice and this permission notice
are preserved on all copies.
Permission is granted to copy and distribute modified versions of this
manual page under the conditions for verbatim copying, provided that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.
Permission is granted to copy and distribute translations of this
manual page into another language, under the above conditions for
modified versions, except that this permission notice may be stated in
a translation approved by the Foundation.
Free Software Foundation Mar 11 2022 RWARRAY(3am)
RWARRAY(3am) GNU Awk Extension Modules RWARRAY(3am)
NAME
writea, reada, writeall, readall - write and read gawk arrays to/from
files
SYNOPSIS
@load "rwarray"
ret = writea(file, array)
ret = reada(file, array)
ret = writeall(file)
ret = readall(file)
DESCRIPTION
The rwarray extension adds functions named writea(), reada(),
writeall(), and readall(), as follows.
writea()
This function takes a string argument, which is the name of the
file to which dump the array, and the array itself as the second
argument. writea() understands multidimensional arrays. It
returns one on success, or zero upon failure.
reada()
is the inverse of writea(); it reads the file named as its first
argument, filling in the array named as the second argument. It
clears the array first. Here too, the return value is one on
success and zero upon failure.
writeall()
This function takes a string argument, which is the name of the
file to which dump the state of all variables. Calling this
function is completely equivalent to calling writea() with the
second argument equal to SYMTAB. It returns one on success, or
zero upon failure.
readall()
This function takes a string argument, which is the name of the
file from which to read the contents of various global
variables. For each variable in the file, the data is loaded
unless the variable already exists. If the variable already
exists, the data for that variable in the file is ignored. It
returns one on success, or zero upon failure.
NOTES
The array created by reada() is identical to that written by writea()
in the sense that the contents are the same. However, due to
implementation issues, the array traversal order of the recreated array
will likely be different from that of the original array. As array
traversal order in AWK is by default undefined, this is not
(technically) a problem. If you need to guarantee a particular
traversal order, use the array sorting features in gawk to do so.
The file contains binary data. All integral values are written in
network byte order. However, double precision floating-point values
are written as native binary data. Thus, arrays containing only string
data can theoretically be dumped on systems with one byte order and
restored on systems with a different one, but this has not been tried.
EXAMPLE
@load "rwarray"
...
ret = writea("arraydump.bin", array)
...
ret = reada("arraydump.bin", array)
...
ret = writeall("globalstate.bin")
...
ret = readall("globalstate.bin")
SEE ALSO
GAWK: Effective AWK Programming, filefuncs(3am), fnmatch(3am),
fork(3am), inplace(3am), ordchr(3am), readdir(3am), readfile(3am),
revoutput(3am), time(3am).
AUTHOR
Arnold Robbins, arnold@skeeve.com.
COPYING PERMISSIONS
Copyright (C) 2012, 2013, 2018, 2022 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of this
manual page provided the copyright notice and this permission notice
are preserved on all copies.
Permission is granted to copy and distribute modified versions of this
manual page under the conditions for verbatim copying, provided that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.
Permission is granted to copy and distribute translations of this
manual page into another language, under the above conditions for
modified versions, except that this permission notice may be stated in
a translation approved by the Foundation.
Free Software Foundation Mar 11 2022 RWARRAY(3am)