### 13.3 Functions and Variables for File Input and Output

Function: appendfile (filename)

  Appends a console transcript to filename. `appendfile` is the same as `writefile`, except that the transcript file, if it exists, is always appended.

  `closefile` closes the transcript file opened by `appendfile` or `writefile`.

  Categories:File output ·Console interaction ·

Function: batch
`batch` (filename)
`batch` (filename, option)
`batch` (S)
`batch` (S, option)

  `batch(filename)` reads Maxima expressions from filename and evaluates them. `batch` searches for filename in the list `file_search_maxima`. See also `file_search`.

  `batch(S)` reads Maxima expressions from the input stream S as created by `openr`. The behavior of `batch` in this case is the same as if the input were a file name, and in the remainder of this description, what is said about input files applies to input streams as well, except that the comments about searching for files do not apply to streams.

  `batch(filename, `demo`)` is like `demo(filename)`. In this case `batch` searches for filename in the list `file_search_demo`. See `demo`.

  `batch(filename, `test`)` is like `run_testsuite` with the option `display_all=true`. For this case `batch` searches filename in the list `file_search_maxima` and not in the list `file_search_tests` like `run_testsuite`. Furthermore, `run_testsuite` runs tests which are in the list `testsuite_files`. With `batch` it is possible to run any file in a test mode, which can be found in the list `file_search_maxima`. This is useful, when writing a test file.

  filename comprises a sequence of Maxima expressions, each terminated with `;` or `$`. The special variable `%` and the function `%th` refer to previous results within the file. The file may include `:lisp` constructs. Spaces, tabs, and newlines in the file are ignored. A suitable input file may be created by a text editor or by the `stringout` function.

  `batch` reads each input expression from filename, displays the input to the console, computes the corresponding output expression, and displays the output expression. Input labels are assigned to the input expressions and output labels are assigned to the output expressions. `batch` evaluates every input expression in the file unless there is an error. If user input is requested (by `asksign` or `askinteger`, for example) `batch` pauses to collect the requisite input and then continue.

  It may be possible to halt `batch` by typing `control-C` at the console. The effect of `control-C` depends on the underlying Lisp implementation.

  `batch` has several uses, such as to provide a reservoir for working command lines, to give error-free demonstrations, or to help organize one’s thinking in solving complex problems.

  `batch` evaluates its arguments.

  When called with no second argument or with the option `demo`, `batch` returns the path of filename, if the argument is a file name, or the path of the file for which the input stream was opened, if the argument is a file input stream. If the argument is a string input stream, a representation of the input stream is returned.

  When called with the option `test`, the return value is a an empty list `[]` or a list with filename and the numbers of the tests which have failed.

  See also `load`, `batchload`, and `demo`.

  Categories:Session management ·File input ·

Function: batchload
`batchload` (filename)
`batchload` (S)

  Reads Maxima expressions from input file filename or input stream S and evaluates them, without displaying the input or output expressions and without assigning labels to output expressions. Printed output (such as produced by `print` or `describe`)) is displayed, however.

  The special variable `%` and the function `%th` refer to previous results from the interactive interpreter, not results within the file. The file cannot include `:lisp` constructs.

  `batchload` evaluates its argument.

  `batchload` returns the path of filename, if the argument is a file name, or the path of the file for which the input stream was opened, if the argument is a file input stream. If the argument is a string input stream, a representation of the input stream is returned.

  See also `batch`, and `load`.

  Categories:Session management ·File input ·

Function: closefile ()

  Closes the transcript file opened by `writefile` or `appendfile`.

  Categories:File output ·Console interaction ·

Option variable: file_output_append

  Default value: `false`

  `file_output_append` governs whether file output functions append or truncate their output file. When `file_output_append` is `true`, such functions append to their output file. Otherwise, the output file is truncated.

  `save`, `stringout`, and `with_stdout` respect `file_output_append`. Other functions which write output files do not respect `file_output_append`. In particular, plotting and translation functions always truncate their output file, and `tex` and `appendfile` always append.

  Categories:File output ·Global flags ·

Function: filename_merge (path, filename)

  Constructs a modified path from path and filename. If the final component of path is of the form `###.something`, the component is replaced with `filename.something`. Otherwise, the final component is simply replaced by filename.

  The result is a Lisp pathname object.

  Categories:File input ·File output ·

Function: file_search
`file_search` (filename)
`file_search` (filename, pathlist)

  `file_search` searches for the file filename and returns the path to the file (as a string) if it can be found; otherwise `file_search` returns `false`. `file_search (filename)` searches in the default search directories, which are specified by the `file_search_maxima`, `file_search_lisp`, and `file_search_demo` variables.

  `file_search` first checks if the actual name passed exists, before attempting to match it to “wildcard” file search patterns. See `file_search_maxima` concerning file search patterns.

  The argument filename can be a path and file name, or just a file name, or, if a file search directory includes a file search pattern, just the base of the file name (without an extension). For example,

      file_search ("/home/wfs/special/zeta.mac");
      file_search ("zeta.mac");
      file_search ("zeta");

  all find the same file, assuming the file exists and `/home/wfs/special/###.mac` is in `file_search_maxima`.

  `file_search (filename, pathlist)` searches only in the directories specified by pathlist, which is a list of strings. The argument pathlist supersedes the default search directories, so if the path list is given, `file_search` searches only the ones specified, and not any of the default search directories. Even if there is only one directory in pathlist, it must still be given as an one-element list.

  The user may modify the default search directories. See `file_search_maxima`.

  `file_search` is invoked by `load` with `file_search_maxima` and `file_search_lisp` as the search directories.

  Categories:File input ·

Option variable: file_search_maxima
Option variable: file_search_lisp
Option variable: file_search_demo
Option variable: file_search_usage
Option variable: file_search_tests

  These variables specify lists of directories to be searched by `load`, `demo`, and some other Maxima functions. The default values of these variables name various directories in the Maxima installation.

  The user can modify these variables, either to replace the default values or to append additional directories. For example,

      file_search_maxima: ["/usr/local/foo/###.mac",
          "/usr/local/bar/###.mac"]$

  replaces the default value of `file_search_maxima`, while

      file_search_maxima: append (file_search_maxima,
          ["/usr/local/foo/###.mac", "/usr/local/bar/###.mac"])$

  appends two additional directories. It may be convenient to put such an expression in the file `maxima-init.mac` so that the file search path is assigned automatically when Maxima starts. See also Introduction for Runtime Environment.

  Multiple filename extensions and multiple paths can be specified by special “wildcard” constructions. The string `###` expands into the sought-after name, while a comma-separated list enclosed in curly braces `{foo,bar,baz}` expands into multiple strings. For example, supposing the sought-after name is `neumann`,

      "/home/{wfs,gcj}/###.{lisp,mac}"

  expands into `/home/wfs/neumann.lisp`, `/home/gcj/neumann.lisp`, `/home/wfs/neumann.mac`, and `/home/gcj/neumann.mac`.

  Categories:File input ·Global variables ·

Function: file_type (filename)

  Returns a guess about the content of filename, based on the filename extension. filename need not refer to an actual file; no attempt is made to open the file and inspect the content.

  The return value is a symbol, either `object`, `lisp`, or `maxima`. If the extension is matches one of the values in `file_type_maxima`, `file_type` returns `maxima`. If the extension matches one of the values in `file_type_lisp`, `file_type` returns `lisp`. If none of the above, `file_type` returns `object`.

  See also `pathname_type`.

  See `file_type_maxima` and `file_type_lisp` for the default values.

  Examples:

      (%i2) map('file_type,
                ["test.lisp", "test.mac", "test.dem", "test.txt"]);
      (%o2)            [lisp, maxima, maxima, object]

  Categories:File input ·

Option variable: file_type_lisp

  Default value: `[l, lsp, lisp]`

  `file_type_lisp` is a list of file extensions that maxima recognizes as denoting a Lisp source file.

  See also `file_type`.

Option variable: file_type_maxima

  Default value: `[mac, mc, demo, dem, dm1, dm2, dm3, dmt, wxm]`

  `file_type_maxima` is a list of file extensions that maxima recognizes as denoting a Maxima source file.

  See also `file_type`.

Function: load (filename)

  Evaluates expressions in filename, thus bringing variables, functions, and other objects into Maxima. The binding of any existing object is clobbered by the binding recovered from filename.

  filename must be a string, symbol, or Lisp pathname (as created by `filename_merge`). To find the file, `load` calls `file_search` with `file_search_maxima` and `file_search_lisp` as the search directories. If `load` succeeds, it returns the name of the file. Otherwise `load` prints an error message.

  `load` works equally well for Lisp code and Maxima code. Files created by `save`, `translate_file`, and `compile_file`, which create Lisp code, and `stringout`, which creates Maxima code, can all be processed by `load`. `load` calls `loadfile` to load Lisp files and `batchload` to load Maxima files.

  `load` does not recognize `:lisp` constructs in Maxima files, and while processing filename, the global variables `_`, `__`, `%`, and `%th` have whatever bindings they had when `load` was called.

  Note also that structures will only be read back as structures if they have been defined by `defstruct` before the `load` command is called.

  See also `loadfile`, for Lisp files; and `batch`, `batchload`, and `demo`. for Maxima files.

  See `file_search` for more detail about the file search mechanism. The `numericalio` chapter describes many functions for loading csv and other data files.

  During Maxima file loading, the variable `load_pathname` is bound to the pathname of the file being loaded.

  `load` evaluates its argument.

  Categories:Session management ·File input ·

System variable: load_pathname

  Default value: `false`

  When a file is loaded with the functions `load`, `loadfile` or `batchload` the system variable `load_pathname` is bound to the pathname of the file which is processed.

  The variable `load_pathname` can be accessed from the file during the loading.

  Example:

  Suppose we have a batchfile `test.mac` in the directory

  `"/home/dieter/workspace/mymaxima/temp/"` with the following commands

      print("The value of load_pathname is: ", load_pathname)$
      print("End of batchfile")$

  then we get the following output

      (%i1) load("/home/dieter/workspace/mymaxima/temp/test.mac")$
      The value of load_pathname is:
                         /home/dieter/workspace/mymaxima/temp/test.mac
      End of batchfile

  Categories:File input ·

Function: loadfile (filename)

  Evaluates Lisp expressions in filename. `loadfile` does not invoke `file_search`, so `filename` must include the file extension and as much of the path as needed to find the file.

  `loadfile` can process files created by `save`, `translate_file`, and `compile_file`. The user may find it more convenient to use `load` instead of `loadfile`.

  Categories:Session management ·File input ·

Option variable: loadprint

  Default value: `true`

  `loadprint` tells whether to print a message when a file is loaded.

  - When `loadprint` is `true`, always print a message.
  - When `loadprint` is `'loadfile`, print a message only if a file is loaded by the function `loadfile`.
  - When `loadprint` is `'autoload`, print a message only if a file is automatically loaded. See `setup_autoload`.
  - When `loadprint` is `false`, never print a message.
  Categories:File input ·Global flags ·

Function: directory (path)

  Returns a list of the files and directories found in path in the file system.

  path may contain wildcard characters (i.e., characters which represent unspecified parts of the path), which include at least the asterisk on most systems, and possibly other characters, depending on the system.

  `directory` relies on the Lisp function DIRECTORY, which may have implementation-specific behavior.

  Categories:File input ·

Function: pathname_directory (pathname)
Function: pathname_name (pathname)
Function: pathname_type (pathname)

  These functions return the components of pathname.

  Examples:

      (%i1) pathname_directory("/home/dieter/maxima/changelog.txt");
      (%o1)                 /home/dieter/maxima/
      (%i2) pathname_name("/home/dieter/maxima/changelog.txt");
      (%o2)                       changelog
      (%i3) pathname_type("/home/dieter/maxima/changelog.txt");
      (%o3)                          txt

  Categories:File input ·

Function: printfile (path)

  Prints the file named by path to the console. path may be a string or a symbol; if it is a symbol, it is converted to a string.

  If path names a file which is accessible from the current working directory, that file is printed to the console. Otherwise, `printfile` attempts to locate the file by appending path to each of the elements of `file_search_usage` via `filename_merge`.

  `printfile` returns path if it names an existing file, or otherwise the result of a successful filename merge.

  Categories:File input ·Console interaction ·

Function: save
`save` (filename, name_1, name_2, name_3, …)
`save` (filename, values, functions, labels, …)
`save` (filename, [m, n])
`save` (filename, name_1=expr_1, …)
`save` (filename, all)
`save` (filename, name_1=expr_1, name_2=expr_2, …)

  Stores the current values of name_1, name_2, name_3, …, in filename. The arguments are the names of variables, functions, or other objects. If a name has no value or function associated with it, it is ignored. `save` returns filename.

  `save` stores data in the form of Lisp expressions. If filename ends in `.lisp` the data stored by `save` may be recovered by `load (filename)`. See `load`.

  The global flag `file_output_append` governs whether `save` appends or truncates the output file. When `file_output_append` is `true`, `save` appends to the output file. Otherwise, `save` truncates the output file. In either case, `save` creates the file if it does not yet exist.

  The special form `save (filename, values, functions, labels, ...)` stores the items named by `values`, `functions`, `labels`, etc. The names may be any specified by the variable `infolists`. `values` comprises all user-defined variables.

  The special form `save (filename, [m, n])` stores the values of input and output labels m through n. Note that m and n must be literal integers. Input and output labels may also be stored one by one, e.g., `save ("foo.1", %i42, %o42)`. `save (filename, labels)` stores all input and output labels. When the stored labels are recovered, they clobber existing labels.

  The special form `save (filename, name_1=expr_1, name_2=expr_2, ...)` stores the values of expr_1, expr_2, …, with names name_1, name_2, … It is useful to apply this form to input and output labels, e.g., `save ("foo.1", aa=%o88)`. The right-hand side of the equality in this form may be any expression, which is evaluated. This form does not introduce the new names into the current Maxima environment, but only stores them in filename.

  These special forms and the general form of `save` may be mixed at will. For example, `save (filename, aa, bb, cc=42, functions, [11, 17])`.

  The special form `save (filename, all)` stores the current state of Maxima. This includes all user-defined variables, functions, arrays, etc., as well as some automatically defined items. The saved items include system variables, such as `file_search_maxima` or `showtime`, if they have been assigned new values by the user; see `myoptions`.

  `save` evaluates filename and quotes all other arguments.

  Categories:Session management ·File output ·

Function: stringout
`stringout` (filename, expr_1, expr_2, expr_3, …)
`stringout` (filename, [m, n])
`stringout` (filename, input)
`stringout` (filename, functions)
`stringout` (filename, values)

  `stringout` writes expressions to a file in the same form the expressions would be typed for input. The file can then be used as input for the `batch` or `demo` commands, and it may be edited for any purpose. `stringout` can be executed while `writefile` is in progress.

  The global flag `file_output_append` governs whether `stringout` appends or truncates the output file. When `file_output_append` is `true`, `stringout` appends to the output file. Otherwise, `stringout` truncates the output file. In either case, `stringout` creates the file if it does not yet exist.

  The general form of `stringout` writes the values of one or more expressions to the output file. Note that if an expression is a variable, only the value of the variable is written and not the name of the variable. As a useful special case, the expressions may be input labels (`%i1`, `%i2`, `%i3`, …) or output labels (`%o1`, `%o2`, `%o3`, …).

  If `grind` is `true`, `stringout` formats the output using the `grind` format. Otherwise the `string` format is used. See `grind` and `string`.

  The special form `stringout (filename, [m, n])` writes the values of input labels m through n, inclusive.

  The special form `stringout (filename, input)` writes all input labels to the file.

  The special form `stringout (filename, functions)` writes all user-defined functions (named by the global list `functions`)) to the file.

  The special form `stringout (filename, values)` writes all user-assigned variables (named by the global list `values`)) to the file. Each variable is printed as an assignment statement, with the name of the variable, a colon, and its value. Note that the general form of `stringout` does not print variables as assignment statements.

  Categories:Session management ·File output ·

Function: with_stdout
`with_stdout` (f, expr_1, expr_2, expr_3, …)
`with_stdout` (s, expr_1, expr_2, expr_3, …)

  Evaluates expr_1, expr_2, expr_3, … and writes any output thus generated to a file f or output stream s. The evaluated expressions are not written to the output. Output may be generated by `print`, `display`, `grind`, among other functions.

  The global flag `file_output_append` governs whether `with_stdout` appends or truncates the output file f. When `file_output_append` is `true`, `with_stdout` appends to the output file. Otherwise, `with_stdout` truncates the output file. In either case, `with_stdout` creates the file if it does not yet exist.

  `with_stdout` returns the value of its final argument.

  See also `writefile` and `display2d`.

      (%i1) with_stdout ("tmp.out", for i:5 thru 10 do
            print (i, "! yields", i!))$
      (%i2) printfile ("tmp.out")$
      5 ! yields 120
      6 ! yields 720
      7 ! yields 5040
      8 ! yields 40320
      9 ! yields 362880
      10 ! yields 3628800

  Categories:File output ·

Function: writefile (filename)

  Begins writing a transcript of the Maxima session to filename. All interaction between the user and Maxima is then recorded in this file, just as it appears on the console.

  As the transcript is printed in the console output format, it cannot be reloaded into Maxima. To make a file containing expressions which can be reloaded, see `save` and `stringout`. `save` stores expressions in Lisp form, while `stringout` stores expressions in Maxima form.

  The effect of executing `writefile` when filename already exists depends on the underlying Lisp implementation; the transcript file may be clobbered, or the file may be appended. `appendfile` always appends to the transcript file.

  It may be convenient to execute `playback` after `writefile` to save the display of previous interactions. As `playback` displays only the input and output variables (`%i1`, `%o1`, etc.), any output generated by a print statement in a function (as opposed to a return value) is not displayed by `playback`.

  `closefile` closes the transcript file opened by `writefile` or `appendfile`.

  Categories:File output ·Console interaction ·