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Some folks might think: “you still use RCS”?!? And we will say, hey, at least we switched from SCCS to RCS back in … I think it was around 1994 ... at least we are keeping up! :-) :-) :-) Logs say that SCCS version 18 became RCS version 19 on 1994 March 18. RCS served us well. But now it is time to move on. And so we are switching to git. Calc releases produce a lot of file changes. In the 125 releases of calc since 1996, when I started managing calc releases, there have been 15473 file mods!
204 lines
6.9 KiB
Plaintext
204 lines
6.9 KiB
Plaintext
NAME
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fpathopen - open an absolute or relative filename along a search path
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SYNOPSIS
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fpathopen(filename, mode [,searchpath])
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TYPES
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filename string
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mode string
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searchpath string
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return file
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DESCRIPTION
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This function opens the file named filename, potentially searching
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for the file along a search path given by searchpath. If searchpath
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is not given, then CALCPATH search path is used.
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If the filename is absolute, or it has an implied path, then
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searchpath is ignored and the filename is opened directly.
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Absolute filenames, and filenames with an implied path are files
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that begin with:
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/ # absolute path
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./ # implied path through the current working directory
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../ # implied path through the current working directory parent
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~ # absolute path going through a home directory
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A search path is a :-separated list of directories used to search for
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a filename. For example:
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fpathopen("whey", "r", ".:/tmp:/var/tmp:~chongo/pub:~/tmp");
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will cause this function to open the first readable file it
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files while searching through these paths in order:
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./whey
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/tmp/whey
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/var/tmp/whey
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~chongo/pub/whey
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~/tmp/whey
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IMPORTANT NOTE:
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This function searches along a path by attempting
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to open files under the given mode. If the mode allows for
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writing and a file can be created, then that file is returned.
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This call open "./gleet" for writing if the current directory is
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writable, even if "./gleet" did not previously exist:
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fpathopen("gleet", "r", ".:/tmp:/var/tmp:~chongo/pub:~/tmp");
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This call will likely open (and create if needded) for appending,
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the file "/tmp/log" assuming that the user is not allowed to
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create files in the previous system directories:
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fpathopen("log", "a", "/:/etc:/bin:/usr/bin:/tmp");
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The CALCPATH search path is taken from the $CALCPATH environment
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variable or if no such variable exists, a compiled in default search
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path is used. See "help environment" and "help calcpath" for more
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information on CALCPATH.
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It should be noted that while CALCPATH is typically used to find
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resource files (*.cal files), this function is not restricted those
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files. Any filename may be opened.
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A file can be opened for either reading, writing, or appending.
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The mode is controlled by the mode flag as follows:
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allow allow file is positioned file(*)
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mode reading writing truncated at mode
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---- ------- ------- --------- --------- ----
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r Y N N beginning text
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rb Y N N beginning binary
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r+ Y N N beginning text
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r+b Y N N beginning binary
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rb+ Y N N beginning binary
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w N Y Y beginning text
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wb N Y Y beginning binary
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w+ Y Y Y beginning text
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w+b Y Y Y beginning binary
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wb+ Y Y Y beginning binary
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a N Y Y end text
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ab N Y Y end binary
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a+ Y Y Y end text
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a+b Y Y Y end binary
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ab+ Y Y Y end binary
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(*) NOTE on 'b' / binary/text mode:
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The 'b' or fopen binary mode has no effect on POSIX / Linux
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/ Un*x-like systems. On those systems a text file is the
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same as a binary file (as it should be for any modern-day
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operating system). Adding 'b' to an fopen has no effect
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and is ignored.
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Some non-POSIX systems sucn as MS Windoz treat text files
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and binary files differently. In text mode MS Windoz consider
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"\r\n" and end-of-line character. On an Apple MAC, the
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text mode end-of-line character is "\r".
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Names of files are subject to ~ expansion just like the C or
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Korn shell. For example, the file name:
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~/lib/gleet
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refers to the file 'gleet' under the directory lib located
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in your home directory. The file name:
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~chongo/was_here
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refers to the a file 'was_here' under the home directory of
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the user 'chongo'.
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If the open is successful, a value of type 'file' will be returned.
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You can use the 'isfile' function to test the return value to see
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if the open succeeded. You should assign the return value of fopen
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to a variable for later use. File values can be copied to more than
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one variable, and using any of the variables with the same file value
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will produce the same results.
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Standard input, standard output and standard error are always opened
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and cannot be closed.
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The truth value of an opened file is TRUE.
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If the open is unsuccessful, the numeric value of errno is returned.
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You can the errno() builtin to determine what the errno number means.
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EXAMPLE
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; fd = fpathopen("motd", "r", "/etc:.")
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; print fd
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"/etc/motd"
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; fd
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FILE 3 "/etc/motd" (reading, pos 0)
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; fd2 = fpathopen("lucas.cal", "r")
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; print fd2
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"/usr/share/calc/lucas.cal"
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; fd2
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FILE 4 "/usr/share/calc/lucas.cal" (reading, pos 0)
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; fd3 = fpathopen("randmprime.cal", "r", calcpath())
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; print fd3
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"/usr/share/calc/randmprime.cal"
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; fd3
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FILE 5 "/usr/share/calc/randmprime.cal" (reading, pos 0)
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; fd4 = fpathopen("output", "w", "~/tmp:/tmp:/var/tmp")
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; print fd4
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"/home/chongo/tmp/output"
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; fd4
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FILE 6 "/home/chongo/tmp/output" (writing, pos 0)
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; !mkdir -p /tmp/log
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; !touch /tmp/log/file
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; logfile = fpathopen("log/file", "a", "/tmp:/var/tmp")
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; print logfile
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"/tmp/log/file"
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; logfile
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FILE 7 "/home/chongo/tmp/output" (writing, pos 0)
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; badfile = fpathopen("no_such_file", "r")
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; if (!isfile(badfile)) print "error #" errno(badfile) : \
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":" : strerror(badfile);
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error #2: No such file or directory
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LIMITS
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none
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LINK LIBRARY
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none
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SEE ALSO
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errno, fclose, feof, ferror, fflush, fgetc, fgetline, fgets, files, fopen,
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fprintf, fputc, fputs, fseek, fsize, ftell, isfile, printf, prompt,
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environment, calcpath
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## Copyright (C) 2006 Landon Curt Noll
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##
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## Calc is open software; you can redistribute it and/or modify it under
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## the terms of the version 2.1 of the GNU Lesser General Public License
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## as published by the Free Software Foundation.
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##
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## Calc is distributed in the hope that it will be useful, but WITHOUT
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## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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## Public License for more details.
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##
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## A copy of version 2.1 of the GNU Lesser General Public License is
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## distributed with calc under the filename COPYING-LGPL. You should have
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## received a copy with calc; if not, write to Free Software Foundation, Inc.
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## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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##
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## Under source code control: 2006/05/07 23:56:04
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## File existed as early as: 2006
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##
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## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
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## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
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