In a script , i would like to check if the argument ( $1, $2 inside the script) contain wildcard (*,? etc). how do i do it?
> script_name arg1 arg*
$1 (arg1) does not contain wildcard, but $2 (arg* )contains wildcard. how can i tell in script?
i need to do this is because :
if arg1... (3 Replies)
Here is the command in question for f in $(<uploads); do .
I only want this to execute if uploads is not empty. If uploads is empty I want the script to quit, actually before the for command. If its not apparent uploads is a text file.
Chris (3 Replies)
Hello All,
I have written shell script whcih at the max 3 parameters.
When only one commandline argument and other two command line arguments are passed as empty string like
eg : archive ' ' ' '
Then i need to check whether the commandline... (12 Replies)
How do I check if a file is empty in a sh script
I want to test in my shell script if the output file is empty and if it is do one thing and if it isnt empty do another?
any ideas? (8 Replies)
I have the list of users in user.log, under each user folder there is sub1 folder is there. i want to check whether sub1 is empty or not, if it is empty i have to skip that user user folder and iterate next user folders. i have the sample code,its not giving not proper results.
while read line... (8 Replies)
I need to check if a directory is empty using an if condition
in the pseudocode below
if ; then
else
although i looked at a few forums on this topic, I left feeling a little unclear and i could not use the command successfully
what can i substitute in the if conditon above,... (2 Replies)
If ($argv == “-debug”) then
Echo “in loop”
Endif
But this is not working. If I modify this code and remove “-“, then it works.
Similarly I am getting problem using grep command also
Grep “-debug” Filename
Can someone please help me on how to resolve these... (1 Reply)
hi,
i want to check whether a a variable contains some value or is empty in a shell script. so if the variable contains some value i want to do some job and if the variable doesnt contain any value then i need to skip that job.
here is a sample script
read_filenames.sh contains
... (5 Replies)
All,
I'm writing an argument checking block and running into an error. I want to confirm that $1 is one of two values. Here is what I have:
if ]; then
echo -e "\nPlease check your first augument. You used \"$1\"
which is not recognized. Please see usage:"
usage
... (9 Replies)
Hello
So i have that script collection, in which i have a single script to create a configuration file.
In there, i have multiple occourences of something like this:
prj_title=$(tui-read "What is the TITLE? ($prj_name):")
] && prj_title="${prj_name/_/ }"
They all work as expected, if... (5 Replies)
Discussion started by: sea
5 Replies
LEARN ABOUT CENTOS
sdl_pixelformat
SDL_PixelFormat(3) SDL API Reference SDL_PixelFormat(3)NAME
SDL_PixelFormat - Stores surface format information
STRUCTURE DEFINITION
typedef struct SDL_PixelFormat {
SDL_Palette *palette;
Uint8 BitsPerPixel;
Uint8 BytesPerPixel;
Uint8 Rloss, Gloss, Bloss, Aloss;
Uint8 Rshift, Gshift, Bshift, Ashift;
Uint32 Rmask, Gmask, Bmask, Amask;
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)