ex

This section uses the term edit buffer to describe the current working text. No specific implementation is implied by this term. All editing changes are performed on the edit buffer, and no changes to it shall affect any file until an editor command writes the file. Certain terminals do not have all the capabilities necessary to support the complete ex definition, such as the full-screen editing commands ( visual mode or open mode ). When these commands cannot be supported on such terminals, this condition shall not produce an error message such as "not an editor command" or report a syntax error. The implementation may either accept the commands and produce results on the screen that are the result of an unsuccessful attempt to meet the requirements of this volume of POSIX.1-2017 or report an error describing the terminal-related deficiency. Specify an initial command to be executed in the first edit buffer loaded from an existing file (see the EXTENDED DESCRIPTION section). Implementations may support more than a single -c option. In such implementations, the specified commands shall be executed in the order specified on the command line. Recover the named files (see the EXTENDED DESCRIPTION section). Recovery information for a file shall be saved during an editor or system crash (for example, when the editor is terminated by a signal which the editor can catch), or after the use of an ex preserve command. If no file operands are given and the -t option is not specified, all other options, the EXINIT variable, and any .exrc files shall be ignored; a list of all recoverable files available to the invoking user shall be written, and the editor shall exit normally without further action. Ignore the value of TERM and any implementation default terminal type and assume the terminal is a type incapable of supporting open or visual modes; see the visual command and the description of vi . Suppress the use of the EXINIT environment variable and the reading of any .exrc file; see the EXTENDED DESCRIPTION section. The .exrc files and source files shall be text files consisting of ex commands; see the EXTENDED DESCRIPTION section. By default, the editor shall read lines from the files to be edited without interpreting any of those lines as any form of editor command. Override the system-selected horizontal screen size. See XBD Environment Variables for valid values and results when it is unset or null. Determine a list of ex commands that are executed on editor start-up. See the EXTENDED DESCRIPTION section for more details of the initialization phase. Provide a default value for the internationalization variables that are unset or null. (See XBD Internationalization Variables for the precedence of internationalization variables used to determine the values of locale categories.) If set to a non-empty string value, override the values of all the other internationalization variables. Determine the locale for the behavior of ranges, equivalence classes, and multi-character collating elements within regular expressions. Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multi-byte characters in arguments and input files), the behavior of character classes within regular expressions, the classification of characters as uppercase or lowercase letters, the case conversion of letters, and the detection of word boundaries. Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error. Override the system-selected vertical screen size, used as the number of lines in a screenful and the vertical screen size in visual mode. See XBD Environment Variables for valid values and results when it is unset or null. [XSI) ] ![[Option Start]]( Determine the location of message catalogs for the processing of LC MESSAGES. ![[Option End]]( Determine the preferred command line interpreter for use as t