..

rsh [ -aefhikmnoprstuvx ] [ -o option ] .\|.\|. [ -c string ] [ arg .\|.\|. ]

A blank\^ is a tab or a space . An identifier\^ is a sequence of letters, digits, or underscores starting with a letter or underscore. Identifiers are used as names for aliases , functions , and "named parameters" . A word\^ is a sequence of characters\^ separated by one or more non-quoted metacharacters .

A pipeline\^ is a sequence of one or more commands\^ separated by \(bv . The standard output of each command but the last is connected by a pipe (2) to the standard input of the next command. Each command is run as a separate process; the shell waits for the last command to terminate. The exit status of a pipeline is the exit status of the last command.

A list\^ is a sequence of one or more pipelines separated by ; , & , && , or \(bv\|\(bv , and optionally terminated by ; , & , or \(bv& . Of these five symbols, ; , & , and \(bv& have equal precedence, which is lower than that of && and \(bv\|\(bv . The symbols && and \(bv\|\(bv also have equal precedence. A semicolon ( ; ) causes sequential execution of the preceding pipeline; an ampersand ( & ) causes asynchronous execution of the preceding pipeline (i.e., the shell does not\^ wait for that pipeline to finish). The symbol \(bv& causes asynchronous execution of the preceding command or pipeline with a two-way pipe established to the parent shell. The standard input and output of the spawned command can be written to and read from by the parent Shell using the -p option of the special commands read and print\^ described later. Only one such command can be active at any given time. The symbol && (\| \(bv\|\(bv \^) causes the list\^ following it to be executed only if the preceding pipeline returns a zero (non-zero) value. An arbitrary number of new-lines may appear in a list,\^ instead of semicolons, to delimit commands.

A command\^ is either a simple-command or one of the following. Unless otherwise stated, the value returned by a command is that of the last simple-command executed in the command.

\f3for \f2identifier\^ \*(OK \f3in \f2word\^ .\|.\|. \*(CK \f3do \f2list\^ \f3done Each time a for command is executed, identifier\^ is set to the next word\^ taken from the in word\^ list. If in " word\^" .\|.\|. is omitted, then the for command executes the \f3do \f2list\^ once for each positional parameter that is set (see "Parameter Substitution\^" below). Execution ends when there are no more words in the list.

\f3select \f2identifier\^ \*(OK \f3in \f2word\^ .\|.\|. \*(CK \f3do \f2list\^ \f3done A select command prints on standard error (file descriptor 2), the set of word s, each preceded by a number. If in " word\^" .\|.\|. is omitted, then the positional parameters are used instead (see "Parameter Substitution\^" below). The PS3 prompt is printed and a line is read from the standard input. If this line consists of the number of one of the listed word s, then the value of the parameter identifier\^ is set to the word\^ corresponding to this number. If this line is empty the selection list is printed again. Otherwise the value of the parameter identifier\^ is set to null . The contents of the line read from standard input is saved in the parameter REPLY. The list\^ is executed for each selection until a break\^ or end-of-file\^ is encountered.

\f3case \f2word\^ \f3in \*(OK \f2pattern\^ \*(OK \(bv \ \f2pattern\^ \*(CK .\|.\|. \f3) \f2list\^ \f3;; \*(CK .\|.\|. \f3esac A case command executes the list\^ associated with the first pattern\^ that matches word . The form of the patterns is the same as that used for file-name generation (see "File Name Generation\^" below).

\f3if \f2list\^ \f3then \f2list\^ \*(OK \ \f3elif \f2list\^ \f3then \f2list\^ \*(CK .\|.\|. \ \*(OK \f3else \f2list\^ \*(CK \f3fi The list\^ following \f3if is executed and, if it returns a zero exit status, the list\^ following the first then is executed. Otherwise, the list\^ following \f3elif is executed and, if its value is zero, the list\^ following the next then is executed. Failing that, the else list\^ is executed. If no else list\^ or then list\^ is executed, then the if command returns a zero exit status.

0 \f3while \f2list\^ \f3do \f2list\^ \f3done

\f3until \f2list\^ \f3do \f2list\^ \f3done

A while command repeatedly executes the while list\^ and, if the exit status of the last command in the list is zero, executes the do list ; otherwise the loop terminates. If no commands in the do list\^ are executed, then the while command returns a zero exit status; until may be used in place of while to negate the loop termination test.

\f3(\f2list\^\f3)

Execute list\^ in a separate environment. Note, that if two adjacent open parentheses are needed for nesting, a space must be inserted to avoid arithmetic evaluation as described below. A parenthesized list used as a command argument denotes "process substitution" as described below.

\f3{ \f2list\^\f3;}

list\^ is simply executed. Note that { is a keyword\^ and requires a blank in order to be recognized.

0 \f3function \f2identifier\^ \f3{ \f2list\^ \f3;}

\f2identifier\^ \f3() { \f2list\^ \f3;}

Define a function which is referenced by identifier . The body of the function is the list\^ of commands between { and } . (See Functions\^ below).

\f3time \f2pipeline\^

The pipeline\^ is executed and the elapsed time as well as the user and system time are printed on standard error.

The following keywords are only recognized as the first word of a command and when not quoted:

Aliasing\^ is performed when scripts are read, not while they are executed. Therefore, for an alias to take effect the alias command has to be executed before the command which references the alias is read.

Aliases are frequently used as a short hand for full path names. An option to the aliasing facility allows the value of the alias to be automatically set to the full pathname of the corresponding command. These aliases are called tracked aliases. The value of a tracked alias is defined the first time the corresponding command is looked up and becomes undefined each time the PATH variable is reset. These aliases remain tracked so that the next subsequent reference will redefine the value. Several tracked aliases are compiled into the shell. The -h option of the set command makes each command name which is a valid alias name into a tracked alias.

The following exported aliases are compiled into the shell but can be unset or redefined:

In addition, the value of each "keyword parameter" is checked to see if it begins with a \(ap or if a \(ap appears after a : . In either of these cases a tilde substitution is attempted.

cuts fields 1 and 3 from the files file1 and file2 respectively, pastes the results together, and sends it to the processes process1 and process2 , as well as putting it onto the standard output. Note that the file, which is passed as an argument to the command, is a UNIX pipe (2) so programs that expect to lseek (2) on the file will not work.

The shell supports a limited one-dimensional array facility. An element of an array parameter is referenced by a subscript . A subscript\^ is denoted by a [ , followed by an arithmetic expression\^ (see Arithmetic evaluation below) followed by a ] . The value of all subscripts must be in the range of 0 through 511. Arrays need not be declared. Any reference to a named parameter with a valid subscript is legal and an array will be created if necessary. Referencing an array without a subscript is equivalent to referencing the first element.

The value\^ of a named parameter\^ may also be assigned by writing:

0 If the integer attribute, -i , is set for name\^ the value\^ is subject to arithmetic evaluation as described below.

Positional parameters, parameters denoted by a number, may be assigned values with the set\^ special command. Parameter $0 is set from argument zero when the shell is invoked.

The character $ is used to introduce substitutable parameters .

\f3${\f2parameter\^\f3} The value, if any, of the parameter is substituted. The braces are required when parameter\^ is followed by a letter, digit, or underscore that is not to be interpreted as part of its name or when a named parameter is subscripted. If parameter\^ is one or more digits then it is a positional parameter. A positional parameter of more than one digit must be enclosed in braces. If parameter\^ is \(** or @ , then all the positional parameters, starting with $1 , are substituted (separated by a field separator character). If an array identifier\^ with subscript \(** or @ is used, then the value for each of the elements is substituted (separated by a field separator character).

\f3${#\f2parameter\^\f3} If parameter\^ is \(** or @ , the number of positional parameters is substituted. Otherwise, the length of the value of the parameter\^ is substituted.

\f3${#\f2identifier\f3[*]} The number of elements in the array identifier\^ is substituted.

\f3${\f2parameter\^\f3:-\f2word\^\f3} If parameter\^ is set and is non-null then substitute its value; otherwise substitute word .

\f3${\f2parameter\^\f3:=\f2word\^\f3} If parameter\^ is not set or is null then set it to word ; the value of the parameter is then substituted. Positional parameters may not be assigned to in this way.

\f3${\f2parameter\^\f3:?\f2word\^\f3} If parameter\^ is set and is non-null then substitute its value; otherwise, print word\^ and exit from the shell. If word\^ is omitted then a standard message is printed.

\f3${\f2parameter\^\f3:+\f2word\^\f3} If parameter\^ is set and is non-null then substitute word ; otherwise substitute nothing.

0 \f3${\f2parameter\^\f3#\f2pattern\^\f3}

\f3${\f2parameter\^\f3##\f2pattern\^\f3}

If the Shell pattern\^ matches the beginning of the value of parameter , then the value of this substitution is the value of the parameter\^ with the matched portion deleted; otherwise the value of this parameter\^ is substituted. In the first form the smallest matching pattern is deleted and in the latter form the largest matching pattern is deleted.

0 \f3${\f2parameter\^\f3%\f2pattern\^\f3}

\f3${\f2parameter\^\f3%%\f2pattern\^\f3}

If the Shell pattern\^ matches the end of the value of parameter , then the value of parameter\^ with the matched part deleted; otherwise substitute the value of parameter . In the first form the smallest matching pattern is deleted and in the latter form the largest matching pattern is deleted.

In the above, word\^ is not evaluated unless it is to be used as the substituted string, so that, in the following example, pwd\^ is executed only if d\^ is not set or is null:

If the colon ( : ) is omitted from the above expressions, then the shell only checks whether parameter\^ is set or not.

The following parameters are automatically set by the shell:

The following parameters are used by the shell:

The shell gives default values to \f3\s-1PATH\s+1, \f3\s-1PS1\s+1, \f3\s-1PS2\s+1, \f3\s-1MAILCHECK\s+1, \f3\s-1TMOUT\s+1 and \f3\s-1IFS\s+1, while HOME , SHELL ENV and MAIL are not set at all by the shell (although HOME is\^ set by login (1)). On some systems MAIL and SHELL are also set by login (1)).

0

The special meaning of keywords or aliases can be removed by quoting any character of the keyword. The recognition of function names or special command names listed below cannot be altered by quoting them.

An internal integer representation of a named parameter\^ can be specified with the -i option of the typeset special command. When this attribute is selected the first assignment to the parameter determines the arithmetic base to be used when parameter substitution occurs.

Since many of the arithmetic operators require quoting, an alternative form of the let command is provided. For any command which begins with a (( , all the characters until a matching )) are treated as a quoted expression. More precisely, (( .\|.\|. )) is equivalent to let\^ \f3"\|.\|.\|.\f3".

14 < word Use file word\^ as standard input (file descriptor 0).

> word Use file word\^ as standard output (file descriptor 1). If the file does not exist then it is created; otherwise, it is truncated to zero length.

>\h@-.3m@> word Use file word\^ as standard output. If the file exists then output is appended to it (by first seeking to the end-of-file); otherwise, the file is created.

\f3<\h@-.3m@<\*(OK\f3-\*(CK\f2word The shell input is read up to a line that is the same as word , or to an end-of-file. No parameter substitution, command substitution or file name generation is performed on word . The resulting document, called a here-document , becomes the standard input. If any character of word\^ is quoted, then no interpretation is placed upon the characters of the document; otherwise, parameter and command substitution occurs, \enew-line is ignored, and \e must be used to quote the characters \e , $ , \*` , and the first character of word . If - is appended to <\h@-.3m@< , then all leading tabs are stripped from word\^ and from the document.

<& digit The standard input is duplicated from file descriptor digit (see dup (2)). Similarly for the standard output using >& digit .

<&- The standard input is closed. Similarly for the standard output using >&- .

If one of the above is preceded by a digit, then the file descriptor number referred to is that specified by the digit (instead of the default 0 or 1). For example:

means file descriptor 2 is to be opened for writing as a duplicate of file descriptor 1.

The order in which redirections are specified is significant. The shell evaluates each redirection in terms of the ( "file descriptor" ", " file ) association at the time of evaluation. For example:

first associates file descriptor 1 with file fname\^ . It then associates file descriptor 2 with the file associated with file descriptor 1 (i.e. fname\^ ). If the order of redirections were reversed, file descriptor 2 would be associated with the terminal (assuming file descriptor 1 had been) and then file descriptor 1 would be associated with file fname\^ .

If a command is followed by & and job control is not active, then the default standard input for the command is the empty file /dev/null . Otherwise, the environment for the execution of a command contains the file descriptors of the invoking shell as modified by input/output specifications.

The environment for any simple-command\^ or function may be augmented by prefixing it with one or more parameter assignments. A parameter assignment argument is a word of the form identifier=value . Thus:

are equivalent (as far as the above execution of cmd\^ is concerned).

If the -k flag is set, all\^ parameter assignment arguments are placed in the environment, even if they occur after the command name. The following first prints "a=b c" and then c:

echo \|a=b \|c
set \|-k
echo \|a=b \|c

The function\^ keyword, described in the Commands section above, is used to define shell functions. Shell functions are read in and stored internally. Alias names are resolved when the function is read. Functions are executed like commands with the arguments passed as positional parameters. (See Execution below).

Functions execute in the same process as the caller and share all files, traps ( other than EXIT and ERR ) and present working directory with the caller. A trap set on EXIT inside a function is executed after the function completes. Ordinarily, variables are shared between the calling program and the function. However, the typeset special command used within a function defines local variables whose scope includes the current function and all functions it calls.

The special command return is used to return from function calls. Errors within functions return control to the caller.

Function identifiers can be listed with the -f option of the typeset special command. The text of functions will also be listed. Function can be undefined with the -f option of the unset special command.

Ordinarily, functions are unset when the shell executes a shell script. The -xf option of the typeset command allows a function to be exported to scripts that are executed without a separate invocation of the shell. Functions that need to be defined across separate invocations of the shell should be placed in the ENV file.

If the monitor option of the set command is turned on, an interactive shell associates a job with each pipeline. It keeps a table of current jobs, printed by the jobs command, and assigns them small integer numbers. When a job is started asynchronously with & , the shell prints a line which looks like:

[1] 1234

indicating that the job which was started asynchronously was job number 1 and had one (top-level) process, whose process id was 1234.

This paragraph and the next require features that are not in all versions of UNIX and may not apply. If you are running a job and wish to do something else you may hit the key ^Z (control-Z) which sends a STOP signal to the current job. The shell will then normally indicate that the job has been `Stopped', and print another prompt. You can then manipulate the state of this job, putting it in the background with the bg command, or run some other commands and then eventually bring the job back into the foreground with the foreground command fg . A ^Z takes effect immediately and is like an interrupt in that pending output and unread input are discarded when it is typed.

A job being run in the background will stop if it tries to read from the terminal. Background jobs are normally allowed to produce output, but this can be disabled by giving the command ``stty tostop''. If you set this tty option, then background jobs will stop when they try to produce output like they do when they try to read input.

There are several ways to refer to jobs in the shell. The character % introduces a job name. If you wish to refer to job number 1, you can name it as %1 . Jobs can also be named by prefixes of the string typed in to kill or restart them. Thus, on systems that support job control, ` fg %ed ' would normally restart a suspended ed (1) job, if there were a suspended job whose name began with the string `ed'.

The shell maintains a notion of the current and previous jobs. In output pertaining to jobs, the current job is marked with a + and the previous job with a - . The abbreviation %+ refers to the current job and %- refers to the previous job. %% is also a synonym for the current job.

This shell learns immediately whenever a process changes state. It normally informs you whenever a job becomes blocked so that no further progress is possible, but only just before it prints a prompt. This is done so that it does not otherwise disturb your work.

When you try to leave the shell while jobs are running or stopped, you will be warned that `You have stopped(running) jobs.' You may use the jobs command to see what they are. If you do this or immediately try to exit again, the shell will not warn you a second time, and the stopped jobs will be terminated.

The shell parameter PATH defines the search path for the directory containing the command. Alternative directory names are separated by a colon ( : ). The default path is /bin:/usr/bin: (specifying /bin , /usr/bin , and the current directory in that order). The current directory can be specified by two or more adjacent colons, or by a colon at the beginning or end of the path list. If the command name contains a \f3/ then the search path is not used. Otherwise, each directory in the path is searched for an executable file. If the file has execute permission but is not a directory or an a.out file, it is assumed to be a file containing shell commands. A sub-shell is spawned to read it. All non-exported aliases, functions, and named parameters are removed in this case. If the shell command file doesn't have read permission, or if the setuid and/or setgid bits are set on the file, then the shell executes an agent whose job it is to set up the permissions and execute the shell with the shell command file passed down as an open file. A parenthesized command is also executed in a sub-shell without removing non-exported quantities.

The editing features require that the user's terminal accept `RETURN' as carriage return without line feed and that a space (` ') must overwrite the current character on the screen. ADM terminal users should set the "space - advance" switch to `space'. Hewlett-Packard series 2621 terminal users should set the straps to `bcGHxZ etX'.

The editing modes implement a concept where the user is looking through a window at the current line. The window width is the value of COLUMNS if it is defined, otherwise 80. If the line is longer than the window width minus two, a mark is displayed at the end of the window to notify the user. As the cursor moves and reaches the window boundaries the window will be centered about the cursor. The mark is a > " (<" , * ) if the line extends on the right (left, both) side(s) of the window.

The notation for escape sequences is M- followed by a character. For example, M-f (pronounced Meta f) is entered by depressing ESC (ascii 033 ) followed by `f'. ( M-F would be the notation for ESC followed by `SHIFT' (capital) `F'.)

All edit commands operate from any place on the line (not just at the beginning). Neither the "RETURN" nor the "LINE FEED" key is entered after edit commands except when noted.

0

10 ^F Move cursor forward (right) one character.

10 M-f Move cursor forward one word. (The editor's idea of a word is a string of characters consisting of only letters, digits and underscores.)

10 ^B Move cursor backward (left) one character.

10 M-b Move cursor backward one word.

10 ^A Move cursor to start of line.

10 ^E Move cursor to end of line.

10 ^] char Move cursor to character char on current line.

10 ^X^X Interchange the cursor and mark.

10 erase (User defined erase character as defined by the stty command, usually ^H or # .) Delete previous character.

10 ^D Delete current character.

10 M-d Delete current word.

10 M-^H (Meta-backspace) Delete previous word.

10 M-h Delete previous word.

10 M-^? (Meta-DEL) Delete previous word (if your interrupt character is ^? (DEL, the default) then this command will not work).

10 ^T Transpose current character with next character in emacs mode. Transpose two previous characters in gmacs mode.

10 ^C Capitalize current character.

10 M-c Capitalize current word.

10 M-l Change the current word to lower case.

10 ^K Kill from the cursor to the end of the line. If given a parameter of zero then kill from the start of line to the cursor.

10 ^W Kill from the cursor to the mark.

10 M-p Push the region from the cursor to the mark on the stack.

10 kill (User defined kill character as defined by the stty command, usually ^G or @ .) Kill the entire current line. If two kill characters are entered in succession, all kill characters from then on cause a line feed (useful when using paper terminals).

10 ^Y Restore last item removed from line. (Yank item back to the line.)

10 ^L Line feed and print current line.

10 ^@ (Null character) Set mark.

10 M- (Meta space) Set mark.

10 ^J (New line) Execute the current line.

10 ^M (Return) Execute the current line.

10 eof End-of-file character, normally ^D , will terminate the shell if the current line is null.

10 ^P Fetch previous command. Each time ^P is entered the previous command back in time is accessed.

10 M-< Fetch the least recent (oldest) history line.

10 M-> Fetch the most recent (youngest) history line.

10 ^N Fetch next command. Each time ^N is entered the next command forward in time is accessed.

10 ^R string Reverse search history for a previous command line containing string . If a parameter of zero is given, the search is forward. String is terminated by a "RETURN" or "NEW LINE". If string is omitted, then the next command line containing the most recent string is accessed. In this case a parameter of zero reverses the direction of the search.

10 ^O Operate - Execute the current line and fetch the next line relative to current line from the history file.

10 M- digits (Escape) Define numeric parameter, the digits are taken as a parameter to the next command. The commands that accept a parameter are . , ^F , ^B , erase , ^D , ^K , ^R , ^P , ^N , M-. , M-_ , M-b , M-c , M-d , M-f , M-h and M-^H .

10 M- letter Soft-key - Your alias list is searched for an alias by the name _ letter and if an alias of this name is defined, its value will be inserted on the input queue. The letter must not be one of the above meta-functions.

10 M-. The last word of the previous command is inserted on the line. If preceded by a numeric parameter, the value of this parameter determines which word to insert rather than the last word.

10 M-_ Same as M-. .

10 M-* Attempt file name generation on the current word. An asterisk is appended if the word doesn't contain any special pattern characters.

10 M-ESC Same as M-* .

10 M-= List files matching current word pattern if an asterisk were appended.

10 ^U Multiply parameter of next command by 4.

10 \e Escape next character. Editing characters, the user's erase, kill and interrupt (normally ^? ) characters may be entered in a command line or in a search string if preceded by a \e . The \e removes the next character's editing features (if any).

10 ^V Display version of the shell.

When in vi mode on most systems, canonical processing is initially enabled and the command will be echoed again if the speed is 1200 baud or greater and it contains any control characters or less than one second has elapsed since the prompt was printed. The ESC character terminates canonical processing for the remainder of the command and the user can than modify the command line. This scheme has the advantages of canonical processing with the type-ahead echoing of raw mode.

If the option viraw\^ is also set, the terminal will always have canonical processing disabled. This mode is implicit for systems that do not support two alternate end of line delimiters, and may be helpful for certain terminals.

0

1. Parameter assignment lists preceding the command remain in effect when the command completes.

2. They are executed in a separate process when used within command substitution.

3. Errors in commands preceded by \(dg\(dg cause the script that contains them to abort.

\(dg \f3: \*(OK \f2arg\^ .\|.\|. \*(CK The command only expands parameters. A zero exit code is returned.

\(dg\(dg \f3\|. \f2file\^ \*(OK \f2arg\^ .\|.\|. \*(CK Read and execute commands from file\^ and return. The commands are executed in the current Shell environment. The search path specified by PATH is used to find the directory containing file . If any arguments arg\^ are given, they become the positional parameters. Otherwise the positional parameters are unchanged.

\f3alias \*(OK \f3-tx \*(CK \*(OK \f2name\*(OK \f2=value\^ \*(CK .\|.\|. \*(CK Alias\^ with no arguments prints the list of aliases in the form name=value\^ on standard output. An alias\^ is defined for each name whose value\^ is given. A trailing space in value\^ causes the next word to be checked for alias substitution. The -t flag is used to set and list tracked aliases. The value of a tracked alias is the full pathname corresponding to the given name . The value becomes undefined when the value of PATH is reset but the aliases remained tracked. Without the -t flag, for each name\^ in the argument list for which no value\^ is given, the name and value of the alias is printed. The -x flag is used to set or print exported aliases. An exported alias is defined across sub-shell environments. Alias returns true unless a name\^ is given for which no alias has been defined.

\f3bg \*(OK \f3%\f2job\^ \*(CK This command is only built-in on systems that support job control. Puts the specified job\^ into the background. The current job is put in the background if job\^ is not specified.

\f3break \*(OK \f2n\^ \*(CK Exit from the enclosing for while until or select\^ loop, if any. If n\^ is specified then break n\^ levels.

\f3continue \*(OK \f2n\^ \*(CK Resume the next iteration of the enclosing for while until or select\^ loop. If n\^ is specified then resume at the n -th enclosing loop.

0 \(dg \f3cd \*(OK \f2arg\^ \*(CK

\(dg \f3cd \f2old\^ \f2new\^

This command can be in either of two forms. In the first form it changes the current directory to arg . If arg\^ is - the directory is changed to the previous directory. The shell parameter HOME is the default arg . The parameter PWD is set to the current directory. The shell parameter CDPATH defines the search path for the directory containing arg . Alternative directory names are separated by a colon ( : ). The default path is <null> (specifying the current directory). Note that the current directory is specified by a null path name, which can appear immediately after the equal sign or between the colon delimiters anywhere else in the path list. If arg begins with a \f3/ then the search path is not used. Otherwise, each directory in the path is searched for arg .

The second form of cd substitutes the string new for the string old in the current directory name, PWD and tries to change to this new directory.

The cd\^ command may not be executed by rsh\^.

\f3echo \*(OK \f2arg\^ .\|.\|. \*(CK See echo (1) for usage and description.

\(dg\(dg \f3eval \*(OK \f2arg\^ .\|.\|. \*(CK The arguments are read as input to the shell and the resulting command(s) executed.

\(dg\(dg \f3exec \*(OK \f2arg\^ .\|.\|. \*(CK If arg\^ is given, the command specified by the arguments is executed in place of this shell without creating a new process. Input/output arguments may appear and affect the current process. If no arguments are given the effect of this command is to modify file descriptors as prescribed by the input/output redirection list. In this case, any file descriptor numbers greater than 2 that are opened with this mechanism are closed when invoking another program.

\f3exit \*(OK \f2n\^ \*(CK Causes the shell to exit with the exit status specified by n . If n\^ is omitted then the exit status is that of the last command executed. An end-of-file will also cause the shell to exit except for a shell which has the ignoreeof option (See set below) turned on.

\(dg\(dg \f3export \*(OK \f2name\^ .\|.\|. \*(CK The given name s are marked for automatic export to the environment\^ of subsequently-executed commands.

0 \(dg\(dg \f3fc \*(OK \f3-e \f2ename\^ \*(CK \*(OK \f3-nlr\^ \*(CK \*(OK \f2first\^ \*(CK \*(OK \f2last\^ \*(CK

\(dg\(dg \f3fc -e - \*(OK \f2old\f3\=\f2new\^ \*(CK \*(OK \f2command\^ \*(CK

In the first form, a range of commands from first\^ to last\^ is selected from the last HISTSIZE commands that were typed at the terminal. The arguments first\^ and last\^ may be specified as a number or as a string. A string is used to locate the most recent command starting with the given string. A negative number is used as an offset to the current command number. If the flag -l , is selected, the commands are listed on standard output. Otherwise, the editor program ename\^ is invoked on a file containing these keyboard commands. If ename\^ is not supplied, then the value of the parameter FCEDIT (default /bin/ed) is used as the editor. When editing is complete, the edited command(s) is executed. If last\^ is not specified then it will be set to first . If first\^ is not specified the default is the previous command for editing and -16 for listing. The flag -r reverses the order of the commands and the flag -n suppresses command numbers when listing. In the second form the command\^ is re-executed after the substitution \f2old\^\f3=\f2new\^ is performed.

\f3fg \*(OK \f3%\f2job\^ \*(CK This command is only built-in on systems that support job control. If job\^ is specified it brings it to the foreground. Otherwise, the current job is brought into the foreground.

\f3jobs \*(OK \f3-l\^ \*(CK Lists the active jobs; given the -l options lists process id's in addition to the normal information.

\f3kill \*(OK \f3-\f2sig\^ \*(CK \f2process\^ .\|.\|. Sends either the TERM (terminate) signal or the specified signal to the specified jobs or processes. Signals are either given by number or by names (as given in /usr/include/signal.h , stripped of the prefix ``SIG''). The signal numbers and names are listed by "'" "kill -l" "'." If the signal being sent is TERM (terminate) or HUP (hangup), then the job or process will be sent a CONT (continue) signal if it is stopped. The argument process\^ can be either a process id or a job.

\f3let \f2arg\^ .\|.\|. Each arg is an "arithmetic expression" to be evaluated. All calculations are done as long integers and no check for overflow is performed. Expressions consist of constants, named parameters, and operators. The following set of operators, listed in order of decreasing precedence, have been implemented:

\(dg\(dg \f3newgrp \*(OK \f2arg\^ .\|.\|. \*(CK Equivalent to "exec newgrp" " arg\^" .\|.\|.\^.

\f3print \*(OK \f3-Rnprsu\^\*(OK\f2n \*(CK \*(CK \*(OK \f2arg\^ .\|.\|. \*(CK The shell output mechanism. With no flags or with flag - , the arguments are printed on standard output as described by echo (1). In raw mode, -R or -r , the escape conventions of echo are ignored. The -R option will print all subsequent arguments and options other than -n . The -p option causes the arguments to be written onto the pipe of the process spawned with \(bv& instead of standard output. The -s option causes the arguments to be written onto the history file instead of standard output. The -u flag can be used to specify a one digit file descriptor unit number n\^ on which the output will be placed. The default is 1. If the flag -n is used, no new-line\^ is added to the output.

\f3pwd Equivalent to \f3print -r - $\s-1PWD\s+1

\f3read \*(OK \f3-prsu\^\*(OK \f2n\^ \*(CK \*(CK \*(OK \f2name\f3?\f2prompt\^\f1 \*(CK \*(OK \f2name\^ .\|.\|. \*(CK The shell input mechanism. One line is read and is broken up into words using the characters in IFS as separators. In raw mode, -r, a \e at the end of a line does not signify line continuation. The first word is assigned to the first name , the second word to the second name , etc., with leftover words assigned to the last name . The -p option causes the input line to be taken from the input pipe of a process spawned by the shell using \(bv& . If the -s flag is present, the input will be saved as a command in the history file. The flag -u can be used to specify a one digit file descriptor unit to read from. The file descriptor can be opened with the exec\^ special command. The default value of n\^ is 0. If name is omitted then REPLY is used as the default name. The return code is 0 unless an end-of-file is encountered. An end-of-file with the -p option causes cleanup for this process so that another can be spawned. If the first argument contains a ? , the remainder of this word is used as a prompt\^ when the shell is interactive. If the given file descriptor is open for writing and is a terminal device then the prompt is placed on this unit. Otherwise the prompt is issued on file descriptor 2. The return code is 0 unless an end-of-file is encountered.

\(dg\(dg \f3readonly \*(OK \f2name .\|.\|. \*(CK The given names are marked readonly and these names cannot be changed by subsequent assignment.

\(dg\(dg \f3return \*(OK \f2n\^ \*(CK Causes a shell function to return to the invoking script with the return status specified by n . If n\^ is omitted then the return status is that of the last command executed. If return is invoked while not in a function or a \f3\|. script, then it is the same as an exit .

\f3set \*(OK \f3-aefhkmnostuvx \*(CK \*(OK \f3-o \f2option\^ .\|.\|. \*(CK \*(OK \f2arg\^ .\|.\|. \*(CK The flags for this command have meaning as follows:

\(dg \f3shift \*(OK \f2n\^ \*(CK

The positional parameters from \f3$\f2n\f3+1 .\|.\|. are renamed $1 .\|.\|.\^ , default n\^ is 1. The parameter n\^ can be any arithmetic expression that evaluates to a non-negative number less than or equal to $# .

\f3test \*(OK \f2expr\^ \*(CK

Evaluate conditional expression expr . See test (1) for usage and description. The arithmetic comparison operators are not restricted to integers. They allow any arithmetic expression. Four additional primitive expressions are allowed:

\f3times

Print the accumulated user and system times for the shell and for processes run from the shell.

\f3trap \*(OK \f2arg\^ \*(CK \*(OK \f2sig\^ \*(CK .\|.\|. arg\^ is a command to be read and executed when the shell receives signal(s) sig . (Note that arg\^ is scanned once when the trap is set and once when the trap is taken.) Each sig\^ can be given as a number or as the name of the signal. Trap commands are executed in order of signal number. Any attempt to set a trap on a signal that was ignored on entry to the current shell is ineffective. If arg\^ is omitted or is - , then all trap(s) sig\^ are reset to their original values. If arg\^ is the null string then this signal is ignored by the shell and by the commands it invokes. If sig\^ is ERR then arg\^ will be executed whenever a command has a non-zero exit code. This trap is not inherited by functions. If sig\^ is 0 or EXIT and the trap statement is executed inside the body of a function, then the command arg\^ is executed after the function completes. If sig\^ is 0 or EXIT for a trap set outside any function then the command arg\^ is executed on exit from the shell. The trap command with no arguments prints a list of commands associated with each signal number.

\(dg\(dg \f3typeset \*(OK \f3-HLRZfilprtux\^\*(OK\f2n \*(CK \*(OK \f2name\*(OK \f2=value\^ \*(CK \^ \*(CK .\|.\|. \*(CK When invoked inside a function, a new instance of the parameter name\^ is created. The parameter value and type are restored when the function completes. The following list of attributes may be specified:

\f3ulimit \*(OK \f3-acdfmpst \*(CK \*(OK \f2n\^ \*(CK

\f3umask \*(OK \f2nnn\^ \*(CK The user file-creation mask is set to nnn\^ (see umask (2)). If nnn\^ is omitted, the current value of the mask is printed.

\f3unalias \f2name\^ .\|.\|. The parameters given by the list of name s are removed from the alias\^ list.

\f3unset \*(OK \f3-f \*(CK \f2name\^ .\|.\|. The parameters given by the list of name s are unassigned, i. e., their values and attributes are erased. Readonly variables cannot be unset. If the flag, -f , is set, then the names refer to function\^ names.

\f3wait \*(OK \f2n\^ \*(CK Wait for the specified child process and report its termination status. If n\^ is not given then all currently active child processes are waited for. The return code from this command is that of the process waited for.

\f3whence \*(OK \f3-v \*(CK \f2name\^ .\|.\|. For each name , indicate how it would be interpreted if used as a command name.

The flag, -v , produces a more verbose report.

0

10 -c "\| string\^" If the -c flag is present then commands are read from string .

-s If the -s flag is present or if no arguments remain then commands are read from the standard input. Shell output, except for the output of the Special commands\^ listed above, is written to file descriptor 2.

-i If the -i flag is present or if the shell input and output are attached to a terminal (as told by ioctl (2)) then this shell is interactive . In this case \s-1TERM\s+1 is ignored (so that \f3kill 0 does not kill an interactive shell) and \s-1INTR\s+1 is caught and ignored (so that wait is interruptible). In all cases, \s-1QUIT\s+1 is ignored by the shell.

-r If the -r flag is present the shell is a restricted shell.

The remaining flags and arguments are described under the set command above.

The restrictions above are enforced after \f3.profile and the ENV files are interpreted.

When a command to be executed is found to be a shell procedure, rsh\^ invokes sh\^ to execute it. Thus, it is possible to provide to the end-user shell procedures that have access to the full power of the standard shell, while imposing a limited menu of commands; this scheme assumes that the end-user does not have write and execute permissions in the same directory.

The net effect of these rules is that the writer of the .profile has complete control over user actions, by performing guaranteed setup actions and leaving the user in an appropriate directory (probably not\^ the login directory).

The system administrator often sets up a directory of commands (i.e., /usr/rbin ) that can be safely invoked by rsh . Some systems also provide a restricted editor red .

/etc/profile

/etc/suid_profile

\s-1$HOME\s+1/\f3.profile

/tmp/sh\(**

/dev/null

If a command which is a "tracked alias" is executed, and then a command with the same name is installed in a directory in the search path before the directory where the original command was found, the shell will continue to exec\^ the original command. Use the -t option of the alias\^ command to correct this situation.

Some very old shell scripts contain a ^ as a synonym for the pipe character. \(bv .

If a command is piped into a shell command, then all variables set in the shell command are lost when the command completes.

Using the fc\^ built-in command within a compound command will cause the whole command to disappear from the history file.

The built-in command \f3\|. \f2file\^ reads the whole file before any commands are executed. Therefore, alias and unalias commands in the file will not apply to any functions defined in the file.