I am trying to create a script to write an XML file for Apple's ITMSP Transporter files for uploading metadata to the App Store. Requirements for screenshots are filename, MD5 checksum and filesize in bytes.
MD5 checksum is easy and be can be retrieved with md5 -q image.png
I am however having a hard time trying to get the byte size of the image file. If I use du -k image.png command, it returns the size rounded up in kilo bytes. So for example if the actual size is 5722 bytes, du will return 8 (as in 8K or 8192 bytes) which is not correct. And the default for du is in 512 byte chunks but still rounds the value up (so it will return 16 instead of 8).
I am running Lion OSX 10.7.4.
One easy approach is:
stat -f%z image.png
stat normally spits out a bunch of data, but the %z format just selects the size in bytes.
On OSX do stat -f "%z bytes".
Related
So I have raw image and I am just curious If I can edit such image to save as RGB-32 Packed transparent interlaced raw and what program I could use, there is specification:
Format of RAW image
I have tried using photoshop but then game crashes. Is it even possible? I should get file without thumbnail. I also tried using gimp, free converters and Raw viewer but no luck. Any suggestions?
Edit:
Used photoshop (interleaved with transparency format), game starts but images are just bunch of pixels.
file that i try to prepare (221bits)
We are still not getting a handle on what output format you are really trying to achieve. Let's try generating a file from scratch, to see if we can get there.
So, let's just use simple commands that are available on a Mac and generate some test images from first principles. Start with exactly the same ghost.raw image you shared in your question. We will take the first 12 bytes as the header, and then generate a file full of red pixels and see if that works:
# Grab first 12 bytes from "ghost.raw" and start a new file "red.raw"
head -c 12 ghost.raw > red.raw
# Now generate 512x108 pixels, where red=ff, green=00, blue=01, alpha=fe and append to "red.raw"
perl -E 'say "ff0001fe" x (512*108)' | xxd -r -p >> red.raw
So you can try using red.raw in place of ghost.raw and tell me what happens.
Now try generating a blue file just the same:
# Grab first 12 bytes from "ghost.raw" and start a new file "blue.raw"
head -c 12 ghost.raw > blue.raw
# Now generate 512x108 pixels, where red=00, green=01, blue=ff, alpha=fe and append to "blue.raw"
perl -E 'say "0001fffe" x (512*108)' | xxd -r -p >> blue.raw
And then try blue.raw.
Original Answer
AFAIK, your image is actually 512 pixels wide by 108 pixels tall in RGBA8888 format with a 12-byte header at the start - making 12 + 4*(512 * 108) bytes.
You can convert it to PNG or JPEG with ImageMagick like this:
magick -size 512x108+12 -depth 8 RGBA:ghost.raw result.png
I still don't understand from your question or comments what format you actually want - so if you clarify that, I am hopeful we can get you answered.
Try using online converters. They help most of the time.\
A Website like these can possibly help:
https://www.freeconvert.com/raw-to-png
https://cloudconvert.com/raw-to-png
https://www.zamzar.com/convert/raw-to-png/
Some are specific websites which ask you for detail and some are straight forward conversions.
I have two 100% identical empty .sh shell script files on Mac:
encrypt.sh: 299 bytes
decrypt.sh: 13 bytes (Actually this size is correct, since I have 13 bytes: 11 character + two new line)
The contents of encrypt.sh and its hexdump:
The contents of decrypt.sh and its hexdump:
The file info window of encrypt.sh:
The file info window of decrypt.sh:
They have the exact same hexdump, then how is it possible that they have different sizes?
Mac OS X file system is implementing forks, so the larger one is likely having something specific stored in its resource fork.
Use ls -l# to get more details.
This question already has answers here:
Size() vs ls -la vs du -h which one is correct size?
(3 answers)
Closed 8 years ago.
There is a file named today.log in my server.
ls -l today.log showing 400GB.
du -sh today.log. showing 240GB
What is the difference between ls and du ...
du shows how much disk the file uses. ls shows how big the file is. These two values can be different. Files with holes can take up less space than their size. Most files do not completely fill the blocks of the filesystem, so they take up more space than their size. A file with a single byte still takes up at least one full block. (512 or 1024 bytes, typically.) As an examle, consider a file with a single byte at position 183738475 (randomly typed numbers). That file can be stored on disk using a single block (whenever the kernel queries the filesystem for bytes other than the single byte in the file, the filesystem reports them as being zero, and there is no need to store anything. Not all filesystems work this way.) But the size of the file is 183738475, so ls will report that and du will report how many blocks are used by the filesystem. du -h will report the number of blocks used times the block size converted to a human readable format. Keep in mind that the actual numbers will vary depending on your filesystem. For example:
$ echo > foo; ls -l foo |awk '{print $5}'; du foo; du -h foo
1
8 foo
4.0K foo
This file is one byte in size but consumes 8 blocks on disk, and the block size is 512 so those 8 blocks consume 4k. (My filesystem has been optimized for large files, and small files waste a lot of space.)
Here is my problem, I have a set of big gz log files, the very first info in the line is a datetime text, e.g.: 2014-03-20 05:32:00.
I need to check what set of log files holds a specific data.
For the init I simply do a:
'-query-data-'
zgrep -m 1 '^20140320-04' 20140320-0{3,4}*gz
BUT HOW to do the same with the last line without process the whole file as would be done with zcat (too heavy):
zcat foo.gz | tail -1
Additional info, those logs are created with the data time of it's initial record, so if I want to query logs at 14:00:00 I have to search, also, in files created BEFORE 14:00:00, as a file would be created at 13:50:00 and closed at 14:10:00.
The easiest solution would be to alter your log rotation to create smaller files.
The second easiest solution would be to use a compression tool that supports random access.
Projects like dictzip, BGZF, and csio each add sync flush points at various intervals within gzip-compressed data that allow you to seek to in a program aware of that extra information. While it exists in the standard, the vanilla gzip does not add such markers either by default or by option.
Files compressed by these random-access-friendly utilities are slightly larger (by perhaps 2-20%) due to the markers themselves, but fully support decompression with gzip or another utility that is unaware of these markers.
You can learn more at this question about random access in various compression formats.
There's also a "Blasted Bioinformatics" blog by Peter Cock with several posts on this topic, including:
BGZF - Blocked, Bigger & Better GZIP! – gzip with random access (like dictzip)
Random access to BZIP2? – An investigation (result: can't be done, though I do it below)
Random access to blocked XZ format (BXZF) – xz with improved random access support
Experiments with xz
xz (an LZMA compression format) actually has random access support on a per-block level, but you will only get a single block with the defaults.
File creation
xz can concatenate multiple archives together, in which case each archive would have its own block. The GNU split can do this easily:
split -b 50M --filter 'xz -c' big.log > big.log.sp.xz
This tells split to break big.log into 50MB chunks (before compression) and run each one through xz -c, which outputs the compressed chunk to standard output. We then collect that standard output into a single file named big.log.sp.xz.
To do this without GNU, you'd need a loop:
split -b 50M big.log big.log-part
for p in big.log-part*; do xz -c $p; done > big.log.sp.xz
rm big.log-part*
Parsing
You can get the list of block offsets with xz --verbose --list FILE.xz. If you want the last block, you need its compressed size (column 5) plus 36 bytes for overhead (found by comparing the size to hd big.log.sp0.xz |grep 7zXZ). Fetch that block using tail -c and pipe that through xz. Since the above question wants the last line of the file, I then pipe that through tail -n1:
SIZE=$(xz --verbose --list big.log.sp.xz |awk 'END { print $5 + 36 }')
tail -c $SIZE big.log.sp.xz |unxz -c |tail -n1
Side note
Version 5.1.1 introduced support for the --block-size flag:
xz --block-size=50M big.log
However, I have not been able to extract a specific block since it doesn't include full headers between blocks. I suspect this is nontrivial to do from the command line.
Experiments with gzip
gzip also supports concatenation. I (briefly) tried mimicking this process for gzip without any luck. gzip --verbose --list doesn't give enough information and it appears the headers are too variable to find.
This would require adding sync flush points, and since their size varies on the size of the last buffer in the previous compression, that's too hard to do on the command line (use dictzip or another of the previously discussed tools).
I did apt-get install dictzip and played with dictzip, but just a little. It doesn't work without arguments, creating a (massive!) .dz archive that neither dictunzip nor gunzip could understand.
Experiments with bzip2
bzip2 has headers we can find. This is still a bit messy, but it works.
Creation
This is just like the xz procedure above:
split -b 50M --filter 'bzip2 -c' big.log > big.log.sp.bz2
I should note that this is considerably slower than xz (48 min for bzip2 vs 17 min for xz vs 1 min for xz -0) as well as considerably larger (97M for bzip2 vs 25M for xz -0 vs 15M for xz), at least for my test log file.
Parsing
This is a little harder because we don't have the nice index. We have to guess at where to go, and we have to err on the side of scanning too much, but with a massive file, we'd still save I/O.
My guess for this test was 50000000 (out of the original 52428800, a pessimistic guess that isn't pessimistic enough for e.g. an H.264 movie.)
GUESS=50000000
LAST=$(tail -c$GUESS big.log.sp.bz2 \
|grep -abo 'BZh91AY&SY' |awk -F: 'END { print '$GUESS'-$1 }')
tail -c $LAST big.log.sp.bz2 |bunzip2 -c |tail -n1
This takes just the last 50 million bytes, finds the binary offset of the last BZIP2 header, subtracts that from the guess size, and pulls that many bytes off of the end of the file. Just that part is decompressed and thrown into tail.
Because this has to query the compressed file twice and has an extra scan (the grep call seeking the header, which examines the whole guessed space), this is a suboptimal solution. See also the below section on how slow bzip2 really is.
Perspective
Given how fast xz is, it's easily the best bet; using its fastest option (xz -0) is quite fast to compress or decompress and creates a smaller file than gzip or bzip2 on the log file I was testing with. Other tests (as well as various sources online) suggest that xz -0 is preferable to bzip2 in all scenarios.
————— No Random Access —————— ——————— Random Access ———————
FORMAT SIZE RATIO WRITE READ SIZE RATIO WRITE SEEK
————————— ————————————————————————————— —————————————————————————————
(original) 7211M 1.0000 - 0:06 7211M 1.0000 - 0:00
bzip2 96M 0.0133 48:31 3:15 97M 0.0134 47:39 0:00
gzip 79M 0.0109 0:59 0:22
dictzip 605M 0.0839 1:36 (fail)
xz -0 25M 0.0034 1:14 0:12 25M 0.0035 1:08 0:00
xz 14M 0.0019 16:32 0:11 14M 0.0020 16:44 0:00
Timing tests were not comprehensive, I did not average anything and disk caching was in use. Still, they look correct; there is a very small amount of overhead from split plus launching 145 compression instances rather than just one (this may even be a net gain if it allows an otherwise non-multithreaded utility to consume multiple threads).
Well, you can access randomly a gzipped file if you previously create an index for each file ...
I've developed a command line tool which creates indexes for gzip files which allow for very quick random access inside them:
https://github.com/circulosmeos/gztool
The tool has two options that may be of interest for you:
-S option supervise a still-growing file and creates an index for it as it is growing - this can be useful for gzipped rsyslog files as reduces to zero in the practice the time of index creation.
-t tails a gzip file: this way you can do: $ gztool -t foo.gz | tail -1
Please, note that if the index doesn't exists, this will consume the same time as a complete decompression: but as the index is reusable, next searches will be greatly reduced in time!
This tool is based on zran.c demonstration code from original zlib, so there's no out-of-the-rules magic!
I have plain vanilla CouchDB from Apache, which runs as an App running on a Mac OS X 10.9. If I try to attach an attachment to a document that is above 1 Meg in size, it just hangs and does nothing.
I have tried to use couchdbs on Linux, and there the sky is the limit.
I first thought it had to do with low limits on the mac but it doesn't seem so :
➜ ~ ulimit -a
-t: cpu time (seconds) unlimited
-f: file size (blocks) unlimited
-d: data seg size (kbytes) unlimited
-s: stack size (kbytes) 8192
-c: core file size (blocks) 0
-v: address space (kbytes) unlimited
-l: locked-in-memory size (kbytes) unlimited
-u: processes 709
-n: file descriptors 256
What is causing this ? Why ? And how to fix this ?
Check the config files given by couchdb -c. You probably have this somewhere in them (for some unknown reason):
[couchdb]
max_attachment_size = 1048576 ; bytes
Remove or comment the line and you should be fine.
Or maybe it was compiled with this hardcoded so you could add this line to one of the config file and increase the value.
Update
max_attachment_size is undocumented so probably not safe to use. I leave the original answer as it seems to have solved the problem of the OP but according to the docs, the attachment size should be unlimited. Also attachment_stream_buffer_size is the config key controlling the chunk size of the attachments which might relevant.