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Article contents:== Outdated CHICKEN release This is a manual page for an old and unsupported version of CHICKEN. If you are still using it, please consider migrating to the latest version. You can find the manual for the latest release [[/manual|here]]. [[tags: manual]] [[toc:]] == Unit utils This unit contains a "grab bag" of procedures without a good home, and which don't have to be available by default (as compared to the [[Unit extras|extras]] unit). This unit uses the {{extras}} and {{srfi-13}} units. === Executing shell commands with formatstring and error checking ==== system* <procedure>(system* FORMATSTRING ARGUMENT1 ...)</procedure> Similar to {{(system (sprintf FORMATSTRING ARGUMENT1 ...))}}, but signals an error should the invoked program return a nonzero exit status. === Reading a file's contents ==== read-all <procedure>(read-all [FILE-OR-PORT])</procedure> If {{FILE-OR-PORT}} is a string, then this procedure returns the contents of the file as a string. If {{FILE-OR-PORT}} is a port, all remaining input is read and returned as a string. The port is not closed. If no argument is provided, input will be read from the port that is the current value of {{(current-input-port)}}. === Shell argument quoting ==== qs <procedure>(qs STRING [PLATFORM])</procedure> Escapes {{STRING}} suitably for passing to a shell command on {{PLATFORM}}. {{PLATFORM}} defaults to the value of {{(build-platform)}} and indicates in which style the argument should be quoted. On Windows systems, the string is simply enclosed in double-quote ({{"}}) characters, on UNIXish systems, characters that would have a special meaning to the shell are escaped using backslash ({{\}}). === Dynamic compilation ==== compile-file <procedure>(compile-file FILENAME #!key options output-file load)</procedure> Compiles the Scheme source file {{FILENAME}} into a dynamically loadable library by invoking the {{csc}} compiler driver. If the library can be successfully created and {{load}} is not given or true, the file is loaded into the current Scheme process. {{options}} may be a list of strings which are passed as additional command line options to {{csc}}. If {{output-file}} is not given, then the compiled file is stored in a temporary location and will be deleted when the process exits successfully. When compilation and loading succeeds, the name of the compiled file is returned, otherwise {{#f}} is returned. Notes: * loading the same compiled file multiple times is only supported on Linux in the moment and should be considered unreliable. For this reason, a new temporary file is created for every invocation of {{compile-file}}, unless an explicit output file name is given. * this procedure is compatible to the {{scheme-compile-file}} command in {{emacs}}' {{scheme-mode}}. ==== compile-file-options <parameter>compile-file-options</parameter> A parameter that holds a list of default options that should be given to {{csc}} after invocation of the {{compile-file}} procedure. The initial default options are {{-scrutinize -O2 -d2}}. === Scanning through an input port ==== scan-input-lines <procedure>(scan-input-lines REGEXP [PORT])</procedure> Reads lines from {{PORT}} (defaults to the result of {{(current-input-port)}}) using {{read-line}} and returns the result of {{(irregex-search REGEXP LINE)}}, if the match succeeds. If no match could be found, {{#f}} is returned. {{REGEXP}} may also be a procedure of one argument which is called for each input line and should return a non-false value on success, which will then be the result of the call to {{scan-input-lines}}. === Asking the user for confirmation ==== yes-or-no? <procedure>(yes-or-no? MESSAGE #!key default title abort)</procedure> Prints the string {{MESSAGE}} and asks for entering "yes", "no" or "abort". If running under Windows in GUI mode, then a suitable dialog box is shown. Returns either {{#t}} or {{#f}} depending on whether {{yes}} or {{no}} was entered. The {{default}} keyword argument specifies the default answer that is effective if the user just presses ENTER (or the default button in case of a dialog box). {{title}} specifies the text shown in the caption of the dialog box and is ignored when not running in GUI mode. {{abort}} should be a zero-argument procedure that is called when the user selects "abort". The default value for {{abort}} is the {{reset}} procedure. A value of {{#f}} for {{abort}} disables aborting completely. Previous: [[Unit posix]] Next: [[Unit tcp]] Description of your changes:

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