Sponsored Content
Top Forums UNIX for Dummies Questions & Answers Security issue and temp files Post 302358217 by mojoman on Thursday 1st of October 2009 05:13:29 PM
Old 10-01-2009
Quote:
Originally Posted by Corona688
It's safe enough to touch /etc/passwd, but imagine what would happen if you'd overwrote it instead.

Using that predictable a name for your temp files has another problem though: What if you want to run two instances of your script at once? I usually do something like
Code:
TMPFILE="/tmp/$$-myprogram"

so each process has a different tempfile. That's only a half step away from using mktemp...
1) What does the $$ do?
2) Was the senior administrator write about his example concerning symbolic links? Like I said, when I tried it did not work (symbolic link will not overwrite /etc/passwd since it is already there) I was using a test system so no worries...had it overwritten /etc/passwd I would not be in trouble (smile).
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Tidying up temp files on exit of script

Hi I believe there is a method to remove all temporary files when a KSH script terminates (either expectedly or unexpectedly). I think is some sort of subroutine you can create that runs when the script exits. Can anyone help me with this please? Many thanks Helen :confused: (2 Replies)
Discussion started by: Bab00shka
2 Replies

2. Shell Programming and Scripting

Script to Delete temp files and check file system

Hi all, new to the threads as well as Unix/Linux. I need to create a script that will delete any temporary files as well as check the files on the system for errors or corruption. This is what I have so far and I'm sure that I'm missing things or have the wrong commands. I'm not sure where to go... (3 Replies)
Discussion started by: Bwood1377
3 Replies

3. Shell Programming and Scripting

Joining 3 AWK scripts to avoid use "temp" files

Hi everyone, Looking for a suggestion to improve the below script in which I´ve been working. The thing is I have 3 separated AWK scripts that I need to apply over the inputfile, and for scripts (2) and (3) I have to use a "temp" file as their inputfile (inputfile_temp and inputfile_temp1... (2 Replies)
Discussion started by: cgkmal
2 Replies

4. UNIX for Dummies Questions & Answers

Temp mysql files jamming CPU resources

Hello Friends I am currently facing high CPU usage problem which is making my site extremely slow. Currently I am using a 8GB RAM with 8 cores but, the creation of temporary files is eating away a lot of the CPU resource making the site very slow. The normal CPU load average remains below 2-3... (5 Replies)
Discussion started by: egully
5 Replies

5. Shell Programming and Scripting

temp files

Hi there, As a regular unix user I am forever programming on the command line or writing scripts so that I first write a load of data to a file to read from. In the end I am always left with a bundle of .txt, .tmp which is what I usually call them. As a basic programmmer I was wondering is... (6 Replies)
Discussion started by: cyberfrog
6 Replies

6. Shell Programming and Scripting

Script to temp create files more than inode limit

HI, I am from testing background. I have a scenario of a file generation, through cronjob, on a defined path. After I fill the data as 100 % utilized, my application is generating an empty file on the defined path. # df -kh Filesystem Size Used Avail Use% Mounted on... (3 Replies)
Discussion started by: atulbassi83
3 Replies

7. OS X (Apple)

Safari Temp Internet Files Location

I'm looking for help with finding where plugin data and other page resources are stored on the hard disk in safari 6.0. With the new update, the activity window has been merged into the develop menu under "show page resources" and one cannot access them directly. I tried running opensnoop to see... (3 Replies)
Discussion started by: sakurashinken
3 Replies

8. Shell Programming and Scripting

Backup shell script created temp files .

Hi, I've a script which creates a temp flat file for storing all business dates received on a single day from diff control files sent by source system on that day. e.g on 12th april I receive txns for business day 8,9,10,11 april. I capture this business day and append to a flat file from... (1 Reply)
Discussion started by: manojg9
1 Replies

9. Shell Programming and Scripting

RMTF (ReMove Temp Files)

Heyas As some applications (sed,grep,vi, etc) create some tempfiles, i'd changed a script to this: (sadly i cant find the original post (code) anymore (which just removed 2 'diffrent kinds'), just similar ones - forgot that as i was new to all this) :) ~ $ cat $(which rmtf) #!/bin/sh #... (1 Reply)
Discussion started by: sea
1 Replies

10. Shell Programming and Scripting

Removing large number of temp files

Hi All, I am having a situation now to delete a huge number of temp files created during run times approx. 16700+ files. We have never imagined that we will get this this much big list of files during run time. It worked fine for lesser no of files in the list. But when list is huge we are... (7 Replies)
Discussion started by: mad man
7 Replies
SDL_PixelFormat(3)						 SDL API Reference						SDL_PixelFormat(3)

NAME
SDL_PixelFormat- Stores surface format information STRUCTURE DEFINITION
typedef struct{ SDL_Palette *palette; Uint8 BitsPerPixel; Uint8 BytesPerPixel; Uint32 Rmask, Gmask, Bmask, Amask; Uint8 Rshift, Gshift, Bshift, Ashift; Uint8 Rloss, Gloss, Bloss, Aloss; Uint32 colorkey; Uint8 alpha; } SDL_PixelFormat; STRUCTURE DATA
palette Pointer to the palette, or NULL if the BitsPerPixel>8 BitsPerPixel The number of bits used to represent each pixel in a surface. Usually 8, 16, 24 or 32. BytesPerPixel The number of bytes used to represent each pixel in a surface. Usually one to four. [RGBA]mask Binary mask used to retrieve individual color values [RGBA]loss Precision loss of each color component (2^[RGBA]loss) [RGBA]shift Binary left shift of each color component in the pixel value colorkey Pixel value of transparent pixels alpha Overall surface alpha value DESCRIPTION
A SDL_PixelFormat describes the format of the pixel data stored at the pixels field of a SDL_Surface. Every surface stores a SDL_PixelFor- mat in the format field. If you wish to do pixel level modifications on a surface, then understanding how SDL stores its color information is essential. 8-bit pixel formats are the easiest to understand. Since its an 8-bit format, we have 8 BitsPerPixel and 1 BytesPerPixel. Since BytesPer- Pixel is 1, all pixels are represented by a Uint8 which contains an index into palette->colors. So, to determine the color of a pixel in a 8-bit surface: we read the color index from surface->pixels and we use that index to read the SDL_Color structure from surface->for- mat->palette->colors. Like so: SDL_Surface *surface; SDL_PixelFormat *fmt; SDL_Color *color; Uint8 index; . . /* Create surface */ . . fmt=surface->format; /* Check the bitdepth of the surface */ if(fmt->BitsPerPixel!=8){ fprintf(stderr, "Not an 8-bit surface. "); return(-1); } /* Lock the surface */ SDL_LockSurface(surface); /* Get the topleft pixel */ index=*(Uint8 *)surface->pixels; color=fmt->palette->colors[index]; /* Unlock the surface */ SDL_UnlockSurface(surface); printf("Pixel Color-> Red: %d, Green: %d, Blue: %d. Index: %d ", color->r, color->g, color->b, index); . . Pixel formats above 8-bit are an entirely different experience. They are considered to be "TrueColor" formats and the color information is stored in the pixels themselves, not in a palette. The mask, shift and loss fields tell us how the color information is encoded. The mask fields allow us to isolate each color component, the shift fields tell us the number of bits to the right of each component in the pixel value and the loss fields tell us the number of bits lost from each component when packing 8-bit color component in a pixel. /* Extracting color components from a 32-bit color value */ SDL_PixelFormat *fmt; SDL_Surface *surface; Uint32 temp, pixel; Uint8 red, green, blue, alpha; . . . fmt=surface->format; SDL_LockSurface(surface); pixel=*((Uint32*)surface->pixels); SDL_UnlockSurface(surface); /* Get Red component */ temp=pixel&fmt->Rmask; /* Isolate red component */ temp=temp>>fmt->Rshift;/* Shift it down to 8-bit */ temp=temp<<fmt->Rloss; /* Expand to a full 8-bit number */ red=(Uint8)temp; /* Get Green component */ temp=pixel&fmt->Gmask; /* Isolate green component */ temp=temp>>fmt->Gshift;/* Shift it down to 8-bit */ temp=temp<<fmt->Gloss; /* Expand to a full 8-bit number */ green=(Uint8)temp; /* Get Blue component */ temp=pixel&fmt->Bmask; /* Isolate blue component */ temp=temp>>fmt->Bshift;/* Shift it down to 8-bit */ temp=temp<<fmt->Bloss; /* Expand to a full 8-bit number */ blue=(Uint8)temp; /* Get Alpha component */ temp=pixel&fmt->Amask; /* Isolate alpha component */ temp=temp>>fmt->Ashift;/* Shift it down to 8-bit */ temp=temp<<fmt->Aloss; /* Expand to a full 8-bit number */ alpha=(Uint8)temp; printf("Pixel Color -> R: %d, G: %d, B: %d, A: %d ", red, green, blue, alpha); . . . SEE ALSO
SDL_Surface, SDL_MapRGB SDL
Tue 11 Sep 2001, 23:01 SDL_PixelFormat(3)
All times are GMT -4. The time now is 02:06 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy