NAME fpathopen - open an absolute or relative filename along a search path SYNOPSIS fpathopen(filename, mode [,searchpath]) TYPES filename string mode string searchpath string return file DESCRIPTION This function opens the file named filename, potentially searching for the file along a search path given by searchpath. If searchpath is not given, then CALCPATH search path is used. If the filename is absolute, or it has an implied path, then searchpath is ignored and the filename is opened directly. Absolute filenames, and filenames with an implied path are files that begin with: / # absolute path ./ # implied path through the current working directory ../ # implied path through the current working directory parent ~ # absolute path going through a home directory A search path is a :-separated list of directories used to search for a filename. For example: fpathopen("whey", "r", ".:/tmp:/var/tmp:~chongo/pub:~/tmp"); will cause this function to open the first readable file it files while searching through these paths in order: ./whey /tmp/whey /var/tmp/whey ~chongo/pub/whey ~/tmp/whey IMPORTANT NOTE: This function searches along a path by attempting to open files under the given mode. If the mode allows for writing and a file can be created, then that file is returned. This call open "./fizzbin" for writing if the current directory is writable, even if "./fizzbin" did not previously exist: fpathopen("fizzbin", "r", ".:/tmp:/var/tmp:~chongo/pub:~/tmp"); This call will likely open (and create if needded) for appending, the file "/tmp/log" assuming that the user is not allowed to create files in the previous system directories: fpathopen("log", "a", "/:/etc:/bin:/usr/bin:/tmp"); The CALCPATH search path is taken from the $CALCPATH environment variable or if no such variable exists, a compiled in default search path is used. See "help environment" and "help calcpath" for more information on CALCPATH. It should be noted that while CALCPATH is typically used to find resource files (*.cal files), this function is not restricted those files. Any filename may be opened. A file can be opened for either reading, writing, or appending. The mode is controlled by the mode flag as follows: allow allow file is positioned file(*) mode reading writing truncated at mode ---- ------- ------- --------- --------- ---- r Y N N beginning text rb Y N N beginning binary r+ Y N N beginning text r+b Y N N beginning binary rb+ Y N N beginning binary w N Y Y beginning text wb N Y Y beginning binary w+ Y Y Y beginning text w+b Y Y Y beginning binary wb+ Y Y Y beginning binary a N Y Y end text ab N Y Y end binary a+ Y Y Y end text a+b Y Y Y end binary ab+ Y Y Y end binary (*) NOTE on 'b' / binary/text mode: The 'b' or fopen binary mode has no effect on POSIX / Linux / Un*x-like systems. On those systems a text file is the same as a binary file (as it should be for any modern-day operating system). Adding 'b' to an fopen has no effect and is ignored. Some non-POSIX systems sucn as MS Windoz treat text files and binary files differently. In text mode MS Windoz consider "\r\n" and end-of-line character. On an Apple MAC, the text mode end-of-line character is "\r". Names of files are subject to ~ expansion just like the C or Korn shell. For example, the file name: ~/lib/fizbin refers to the file 'fizbin' under the directory lib located in your home directory. The file name: ~chongo/was_here refers to the a file 'was_here' under the home directory of the user 'chongo'. If the open is successful, a value of type 'file' will be returned. You can use the 'isfile' function to test the return value to see if the open succeeded. You should assign the return value of fopen to a variable for later use. File values can be copied to more than one variable, and using any of the variables with the same file value will produce the same results. Standard input, standard output and standard error are always opened and cannot be closed. The truth value of an opened file is TRUE. If the open is unsuccessful, the numeric value of errno is returned. You can the errno() builtin to determine what the errno number means. EXAMPLE ; fd = fpathopen("motd", "r", "/etc:.") ; print fd "/etc/motd" ; fd FILE 3 "/etc/motd" (reading, pos 0) ; fd2 = fpathopen("lucas.cal", "r") ; print fd2 "/usr/share/calc/lucas.cal" ; fd2 FILE 4 "/usr/share/calc/lucas.cal" (reading, pos 0) ; fd3 = fpathopen("randmprime.cal", "r", calcpath()) ; print fd3 "/usr/share/calc/randmprime.cal" ; fd3 FILE 5 "/usr/share/calc/randmprime.cal" (reading, pos 0) ; fd4 = fpathopen("output", "w", "~/tmp:/tmp:/var/tmp") ; print fd4 "/home/chongo/tmp/output" ; fd4 FILE 6 "/home/chongo/tmp/output" (writing, pos 0) ; !mkdir -p /tmp/log ; !touch /tmp/log/file ; logfile = fpathopen("log/file", "a", "/tmp:/var/tmp") ; print logfile "/tmp/log/file" ; logfile FILE 7 "/home/chongo/tmp/output" (writing, pos 0) ; badfile = fpathopen("no_such_file", "r") ; if (!isfile(badfile)) print "error #" errno(badfile) : \ ":" : strerror(badfile); error #2: No such file or directory LIMITS none LINK LIBRARY none SEE ALSO errno, fclose, feof, ferror, fflush, fgetc, fgetline, fgets, files, fopen, fprintf, fputc, fputs, fseek, fsize, ftell, isfile, printf, prompt, environment, calcpath ## Copyright (C) 2006,2021 Landon Curt Noll ## ## Calc is open software; you can redistribute it and/or modify it under ## the terms of the version 2.1 of the GNU Lesser General Public License ## as published by the Free Software Foundation. ## ## Calc is distributed in the hope that it will be useful, but WITHOUT ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY ## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General ## Public License for more details. ## ## A copy of version 2.1 of the GNU Lesser General Public License is ## distributed with calc under the filename COPYING-LGPL. You should have ## received a copy with calc; if not, write to Free Software Foundation, Inc. ## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. ## ## Under source code control: 2006/05/07 23:56:04 ## File existed as early as: 2006 ## ## chongo /\oo/\ http://www.isthe.com/chongo/ ## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/