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SAM(9.1) SAM(9.1) NAME sam - screen editor with structural regular expressions SYNOPSIS sam [ option ... ] [ files ] sam -r machine sam.save DESCRIPTION Sam is a multi-file editor. It modifies a local copy of a Unix file. The copy is here called a file; a Unix file is distinguished by the trademarked adjective. The files are listed in a menu available through mouse button 3 or the n command. Each file has an associated name, usually the name of the Unix file from which it was read, and a `modified' bit that indicates whether the editor's file agrees with the Unix file. The Unix file is not read into the editor's file until it first becomes the current file--that to which editing commands apply-- whereupon its menu entry is printed. The options are -d Do not download the terminal part of sam. Editing will be done with the command language only, as in ed(1). -r machine Run the host part remotely on the specified machine, the termi- nal part locally. This extends graphic editing to files on ma- chines that don't ordinarily support it or across non-nfs(8) connections. Regular expressions Regular expressions are as in egrep (see gre(1)), with the addition of @ and \n. A regular expression may never contain a literal newline character. The elements of regular expressions are: . Match any character except newline. \n Match newline. \x For any character except n match the character (here x). @ Match any character. [abc] Match any character in the square brackets. \n may be men- tioned. [^abc] Match any character not in the square brackets, but never a new- line. Both these forms accept a range of ASCII characters indi- cated by a dash, as in a-z. ^ Match the null string immediately after a newline. $ Match the null string immediately before a newline. Any other character except newline matches itself. In the following, r1 and r2 are regular expressions. (r1) Match what r1 matches. r1|r2 Match what r1 or what r2 matches. r1* Match zero or more adjacent matches of r1. r1+ Match one or more adjacent matches of r1. r1? Match zero or one matches of r1. The operators *, + and ? are highest precedence, then catenation, then | is lowest. The empty regular expression stands for the last complete expression encountered. A regular expression in sam matches the longest leftmost substring formally matched by the expression. Search- ing in the reverse direction is equivalent to searching backwards with the catenation operations reversed in the expression. Addresses An address identifies a substring in a file. In the following, `char- acter n' means the null string after the n-th character in the file, with 1 the first character in the file. `Line n' means the n-th match, starting at the beginning of the file, of the regular expression (The peculiar properties of a last line without a newline are temporarily undefined.) All files always have a current substring, called dot, that is the default address. Simple Addresses #n The empty string after character n; #0 is the beginning of the file. n Line n. /regexp/ ?regexp? The substring that matches the regular expression, found by looking toward the end (/) or beginning (?) of the file, and if necessary continuing the search from the other end to the start- ing point of the search. The matched substring may straddle the starting point. 0 The string before the first full line. This is not necessarily the null string; see + and - below. $ The null string at the end of the file. . Dot. ' The mark in the file (see the k command below). "regexp" Preceding a simple address (default .), refers to the address evaluated in the unique file whose menu line matches the regular expression. Compound Addresses In the following, a1 and a2 are addresses. a1+a2 The address a2 evaluated starting at the end of a1. a1-a2 The address a2 evaluated looking in the reverse direction start- ing at the beginning of a1. a1,a2 The substring from the beginning of a1 to the end of a2. If a1 is missing, 0 is substituted If a2 is missing, $ is substituted. a1;a2 Like a1,a2, but with a2 evaluated at the end of, and dot set to, a1. The operators + and - are high precedence, while , and ; are low prece- dence. In both + and - forms, if a2 is a line or character address with a missing number, the number defaults to 1. If a1 is missing, is substi- tuted. If both a1 and a2 are present and distinguishable, + may be elided. a2 may be a regular expression; if it is delimited by the ef- fect of the + or - is reversed. It is an error for a compound address to represent a malformed sub- string. Some useful idioms: a1+- (a1-+) selects the line containing the end (beginning) of a1. 0/regexp/ locates the first match of the expression in the file. (The form 0;// sets dot unnecessarily.) ./regexp/// finds the second following occurrence of the expression, and .,/regexp/ extends dot. Commands In the following, text demarcated by slashes represents text delimited by any printable ASCII character except alphanumerics. Any number of trailing delimiters may be elided, with multiple elisions then repre- senting null strings, but the first delimiter must always be present. In any delimited text, newline may not appear literally; \n may be typed for newline; and \/ quotes the delimiter, here Backslash is oth- erwise interpreted literally, except in s commands. Most commands may be prefixed by an address to indicate their range of operation. Those that may not are marked with a below. If a command takes an address and none is supplied, dot is used. The sole exception is the w command, which defaults to 0,$. In the description, `range' is used to represent whatever address is supplied. Many commands set the value of dot as a side effect. If so, it is always set to the `re- sult' of the change: the empty string for a deletion, the new text for an insertion, etc. (but see the s and e commands). Text commands a/text/ or a lines of text . Insert the text into the file after the range. Set dot. c i Same as a, but c replaces the text, while i inserts before the range. d Delete the text in the range. Set dot. s/regexp/text/ Substitute text for the first match to the regular expression in the range. Set dot to the modified range. In text the charac- ter & stands for the string that matched the expression. Back- slash behaves as usual unless followed by a digit: \d stands for the string that matched the subexpression begun by the d-th left parenthesis. If s is followed immediately by a number n, as in s2/x/y/, the n-th match in the range is substituted. If the command is followed by a g, as in s/x/y/g, all matches in the range are substituted. m a1 t a1 Move the range to after a1 (m), or copy it (t). Set dot. Display commands p Print the text in the range. Set dot. = Print the line address and character address of the range. =# Print just the character address of the range. File commands In these commands a file-list may be expressed <Unix-command in which case the file names are taken as words (in the shell sense) generated by the Unix command. * b file-list Set the current file to the first file named in the list that sam also has in its menu. * B file-list Same as b, except that file names not in the menu are entered there, and all file names in the list are examined. * n Print a menu of files. The format is: ' or blank in- di- cat- ing the file is mod- i- fied or clean, - or + in- di- cat- ing the the file is un- read or has been read (in the ter- mi- nal, * means more than one win- dow is open), . or blank in- di- cat- ing the cur- rent file, a blank, and the file name. * D file-list Delete the named files from the menu. If no files are named, the cur- rent file is deleted. It is an error to D a modified file, but a sub- sequent D will delete such a file. I/O Commands * e filename Replace the file by the contents of the named Unix file. Set dot to the beginning of the file. r filename Replace the text in the range by the contents of the named Unix file. Set dot. w filename Write the range (default 0,$) to the named Unix file. * f filename Set the file name and print the resulting menu entry. If the file name is absent from any of these, the current file name is used. e always sets the file name, r and w do so if the file has no name. < Unix-command Replace the range by the standard output of the Unix command. > Unix-command Sends the range to the standard input of the Unix command. | Unix-command Send the range to the standard input, and replace it by the standard output, of the Unix command. * ! Unix-command Run the Unix command. * cd directory Change working directory. If no directory is specified, $HOME is used. In any of <, >, | or !, if the Unix command is omitted the last Unix command (of any type) is substituted. If sam is downloaded, ! sets standard input to and otherwise unassigned output (stdout for ! and >, stderr for all) is placed in and the first few lines are printed. Loops and Conditionals x/regexp/ command For each match of the regular expression in the range, run the command with dot set to the match. Set dot to the last match. If the regular expression and its slashes are omitted, is as- sumed. Null string matches potentially occur before every char- acter of the range and at the end of the range. y/regexp/ command Like x, but run the command for each substring that lies before, between, or after the matches that would be generated by x. There is no default behavior. Null substrings potentially occur before every character in the range. * X/regexp/ command For each file whose menu entry matches the regular expression, run the command. If the expression is omitted, the command is run in every file. * Y/regexp/ command Same as X, but for files that do not match the regular expres- sion, and the expression is required. g/regexp/ command v/regexp/ command If the range contains (g) or does not contain (v) a match for the expression, set dot to the range and run the command. These may be nested arbitrarily deeply, but only one instance of either X or Y may appear in a single command. An empty command in an x or y defaults to p; an empty command in X or Y defaults to f. g and v do not have defaults. Miscellany k Set the current file's mark to the range. Does not set dot. * q Quit. It is an error to quit with modified files, but a second q will succeed. * u n Undo the last n (default 1) top-level commands that changed the contents or name of the current file, and any other file whose most recent change was simultaneous with the current file's change. Successive u's move further back in time. The only commands for which u is ineffective are cd, u, q, w and D. (empty) If the range is explicit, set dot to the range. If sam is down- loaded, the resulting dot is selected on the screen; otherwise it is printed. If no address is specified (the command is a newline) dot is extended in either direction to line boundaries and printed. If dot is thereby unchanged, it is set to .+1 and printed. Grouping and multiple changes Commands may be grouped by enclosing them in braces {}. Commands within the braces must appear on separate lines (no backslashes are re- quired between commands). Semantically, an opening brace is like a command: it takes an (optional) address and sets dot for each sub-com- mand. Commands within the braces are executed sequentially, but changes made by one command are not visible to other commands (see the next section of this manual). Braces may be nested arbitrarily. When a command makes a number of changes to a file, as in x/re/c/text/, the addresses of all changes to the file are computed in the original file. If the changes are in sequence, they are applied to the file. Successive insertions at the same address are catenated into a single insertion composed of the several insertions in the order applied. The terminal What follows refers to behavior of sam when downloaded, that is, when operating as a display editor on a bitmap display. This is the default behavior; invoking sam with the -d (no download) option provides access to the command language only. Each file may have zero or more windows open. Each window is equiva- lent and is updated simultaneously with changes in other windows on the same file. Each window has an independent value of dot, indicated by a highlighted substring on the display. Dot may be in a region not within the window. There is usually a `current window', marked with a dark border, to which typed text and editing commands apply. Text may be typed and edited as in mux(9.1); also the escape key (ESC) selects (sets dot to) text typed since the last mouse button hit. The button 3 menu controls window operations. The top of the menu pro- vides the following operators, each of which prompts with one or more mux-like cursors to prompt for selection of a window or sweeping of a rectangle. `Sweeping' a null rectangle gets a large window, disjoint from the command window or the whole screen, depending on where the null rectangle is. new Create a new, empty file. xerox Create a copy of an existing window. reshape As in mux. close Delete the window. In the last window of a file, close is equivalent to a D for the file. write Equivalent to a w for the file. Below these operators is a list of available files, starting with ~~sam~~, the command window. Selecting a file from the list makes the most recently used window on that file current, unless it is already current, in which case selections cycle through the open windows. If no windows are open on the file, the user is prompted to open one. Files other than ~~sam~~ are marked with one of the characters -+* ac- cording as zero, one, or more windows are open on the file. A further mark appears on the file in the current window and a single quote, ', on a file modified since last write. Nothing can be done without a command window, for which sam prompts initially. The command window is an ordinary window except that text typed to it is interpreted as commands for the editor rather than pas- sive text, and text printed by editor commands appears in it. The be- havior is like mux, with a `command point' that separates commands be- ing typed from previous output. Commands typed in the command window apply to the current open file--the file in the most recently current window. Manipulating text Button 1 changes selection, much like mux. Pointing to a non-current window with button 1 makes it current; within the current window, but- ton 1 selects text, thus setting dot. Double-clicking selects text to the boundaries of words, lines, quoted strings or bracketed strings, depending on the text at the click. Button 2 provides a menu of editing commands: cut Delete dot and save the deleted text in the snarf buffer. paste Replace the text in dot by the contents of the snarf buffer. snarf Save the text in dot in the snarf buffer. look Search forward for the next occurrence of the literal text in dot. If dot is the null string, the text in the snarf buffer is used. The snarf buffer is unaffected. <mux> Exchange snarf buffers with mux. /regexp Search forward for the next match of the last regular expression typed in a command. (Not in command window.) send Send the text in dot, or the snarf buffer if dot is the null string, as if it were typed to the command window. Saves the sent text in the snarf buffer. (Command window only.) scroll noscroll Select whether to reveal automatically text that appears off the end of the command window. (Command window only.) Abnormal termination If sam terminates other than by a q command (by hangup, deleting its layer, etc.), modified files are saved in an executable file, This pro- gram, when executed, asks whether to write each file back to a Unix file. The answer causes writing; anything else skips the file. FILES SEE ALSO ed(1), sed(1), vi(1), gre(1) BUGS The u command undoes characters--and backspaces--typed directly into a file window in unpredictable increments. SAM(9.1)