Sponsored Content
The Lounge What is on Your Mind? Line 2238 Unix V6 Comment: You are not expected to understand this. Post 302311788 by Neo on Wednesday 29th of April 2009 02:08:56 PM
Old 04-29-2009
Line 2238 Unix V6 Comment: You are not expected to understand this.

Here is the famous line 2238 of Unix V6 which is part of some of the most delicate parts of the kernel, context switching.

This comment received huge publicity and just may be the the most famous source code comment in computing history.

Code:
2230	/*
2231	 * If the new process paused because it was
2232	 * swapped out, set the stack level to the last call
3333	 * to savu(u_ssav).  This means that the return
2235	 * actually returns from the last routine which did
2236	 * the savu.
2237	 *
2238	 * You are not expected to understand this.
2239	 */
2240	if(rp->p_flag&SSWAP) {
2241		rp->p_flag =& ~SSWAP;
2242		aretu(u.u_ssav);
2243	}

Ref: Unix Sixth Edition Kernel Source Code, © Western Electric Company
 

10 More Discussions You Might Find Interesting

1. Programming

remove single-line comment

Does anyone knows how to write a program to remove single-line comment in C program? that means it don't read anything behind // (3 Replies)
Discussion started by: Icy002
3 Replies

2. Shell Programming and Scripting

Placing a comment at the beginning of a line

Hello - I am running Linux. I want to place a comment char at the beginning of a line in a file. For example: testvar=`grep username /etc/people sed -e 's/$testvar/#$testvar/g' /etc/people I cannot get the above commands to put a comment at the beginning of the line. Any... (3 Replies)
Discussion started by: mlike
3 Replies

3. UNIX for Dummies Questions & Answers

how to replace a text of line with a comment line

I want to replace this line : "test compare visible] true" and make it "#test compare visible] true". How can I do it ? And it should be checked in many sub folder files also. (6 Replies)
Discussion started by: manoj.b
6 Replies

4. Shell Programming and Scripting

Using sed to comment out line in /etc/vfstab

I am running a script remotely to do the following 1. Kill all processes by a user 2. Uninstall certain packages 3. FTP over a new file 4. Kill a ldap process that is not allowing my /devdsk/c0t0d0s7 slice to un-mount 5. Unmount /h 6. comment out the slice in vfstab 7. newfs the... (9 Replies)
Discussion started by: deaconf19
9 Replies

5. Shell Programming and Scripting

How To comment a line where a word exists

Hi All Can u help me.. My problem is comment (#) a line where a word exists in that line sample: cat /tmp/file.txt monitor 192.168.1.11 Copying files in current directory 1 monitor 192.168.1.1 Copying files in current directory 2 monitor 192.168.1.12 Copying files in current... (2 Replies)
Discussion started by: darren_j
2 Replies

6. Shell Programming and Scripting

Comment a line with SED

I have around 25 hosts and each hosts has 4 instance of jboss and 4 different ip attached to it . I need to make some changes to the startup scripts. Any tips appreciated. I have total of 100 instances which bind to 100 different ip address based on instance name. For example File1 ... (1 Reply)
Discussion started by: gubbu
1 Replies

7. Shell Programming and Scripting

comment a line of the patterns is a the beginning of the line

I need to comment the lines starting with pattern "exclude" or "exclude=". If the work exclude comes at any other part, ignore it. Also, ignore, excludes, excluded etc. Ie only comment the line starting with exclude. File contents. exclude exclude= hi I am excluded excludes excludes= ... (9 Replies)
Discussion started by: anil510
9 Replies

8. Shell Programming and Scripting

Removing the sas comment line using UNIX

I have tried a lot, Need your help guys. SAS Program: data one ; /* Data step */ Input name $; /*Dec variables*/ I want to remove the commented part(/* Data step */) alone. I have tried using sed command but it is deleting the entire line itself. i need unix command to separate this and... (6 Replies)
Discussion started by: saaisiva
6 Replies

9. Shell Programming and Scripting

How to comment a specific line of a file?

Hi, I need to comment out (insert # in the front of a line) a line that has entry Defaults requiretty using command-line as I need to do this on hundreds of servers. From Defaults requiretty To #Defaults requiretty I tried something like below but no luck: Please advise,... (3 Replies)
Discussion started by: prvnrk
3 Replies

10. Shell Programming and Scripting

Echo printing a line in 2 lines; expected to print in one line

Dear All, fileName: therm.txt nc3h7o2h 7/27/98 thermc 3h 8o 2 0g 300.000 5000.000 1390.000 41 1.47017550e+01 1.71731699e-02-5.91205329e-06 9.21842570e-10-5.36438880e-14 2 -2.99988556e+04-4.93387892e+01 2.34710908e+00 4.34517484e-02-2.65357553e-05 3 ... (7 Replies)
Discussion started by: linuxUser_
7 Replies
return(1T)						       Tcl Built-In Commands							return(1T)

__________________________________________________________________________________________________________________________________________________

NAME
return - Return from a procedure SYNOPSIS
return ?-code code? ?-errorinfo info? ?-errorcode code? ?string? _________________________________________________________________ DESCRIPTION
Return immediately from the current procedure (or top-level command or source command), with string as the return value. If string is not specified then an empty string will be returned as result. EXCEPTIONAL RETURN CODES
In addition to the result of a procedure, the return code of a procedure may also be set by return through use of the -code option. In the usual case where the -code option isn't specified the procedure will return normally. However, the -code option may be used to generate an exceptional return from the procedure. Code may have any of the following values: ok (or 0) Normal return: same as if the option is omitted. The return code of the procedure is 0 (TCL_OK). error(1) Error return: the return code of the procedure is 1 (TCL_ERROR). The procedure command behaves in its calling context as if it were the command error result. See below for additional options. return(2) The return code of the procedure is 2 (TCL_RETURN). The procedure command behaves in its calling context as if it were the command return (with no arguments). break(3TCL) The return code of the procedure is 3 (TCL_BREAK). The procedure command behaves in its calling context as if it were the command break. continue(4) The return code of the procedure is 4 (TCL_CONTINUE). The procedure command behaves in its calling context as if it were the command continue. value Value must be an integer; it will be returned as the return code for the current procedure. The -code option is rarely used. It is provided so that procedures that implement new control structures can reflect exceptional condi- tions back to their callers. Two additional options, -errorinfo and -errorcode, may be used to provide additional information during error returns. These options are ignored unless code is error. The -errorinfo option specifies an initial stack trace for the errorInfo variable; if it is not specified then the stack trace left in errorInfo will include the call to the procedure and higher levels on the stack but it will not include any information about the context of the error within the procedure. Typically the info value is supplied from the value left in errorInfo after a catch command trapped an error within the procedure. If the -errorcode option is specified then code provides a value for the errorCode variable. If the option is not specified then errorCode will default to NONE. EXAMPLES
First, a simple example of using return to return from a procedure, interrupting the procedure body. proc printOneLine {} { puts "line 1" ;# This line will be printed. return puts "line 2" ;# This line will not be printed. } Next, an example of using return to set the value returned by the procedure. proc returnX {} {return X} puts [returnX] ;# prints "X" Next, a more complete example, using return -code error to report invalid arguments. proc factorial {n} { if {![string is integer $n] || ($n < 0)} { return -code error "expected non-negative integer, but got "$n"" } if {$n < 2} { return 1 } set m [expr {$n - 1}] set code [catch {factorial $m} factor] if {$code != 0} { return -code $code $factor } set product [expr {$n * $factor}] if {$product < 0} { return -code error "overflow computing factorial of $n" } return $product } Next, a procedure replacement for break. proc myBreak {} { return -code break } SEE ALSO
break(1T), catch(1T), continue(1T), error(1T), proc(1T), source(1T), tclvars(1T) KEYWORDS
break, catch, continue, error, procedure, return ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +--------------------+-----------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +--------------------+-----------------+ |Availability | SUNWTcl | +--------------------+-----------------+ |Interface Stability | Uncommitted | +--------------------+-----------------+ NOTES
Source for Tcl is available on http://opensolaris.org. Tcl 7.0 return(1T)
All times are GMT -4. The time now is 05:54 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy