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If you want to create fast a very big file for testing purposes and you do not care about its content, then you can use this command to create a file of arbitrary size within less than a second. Content of file will be all zero bytes.
The trick is that the content is just not written to the disk, instead the space for it is somehow reserved on operating system level and file system level. It would be filled when first accessed/written (not sure about the mechanism that lies below, but it makes the file creation super fast).
Instead of '1G' as in the example, you could use other modifiers like 200K for kilobytes (1024 bytes), 500M for megabytes (1024 * 1024 bytes), 20G for Gigabytes (1024*1024*1024 bytes), 30T for Terabytes (1024^4 bytes). Also P for Penta, etc...
Command tested under Linux.
This is probably overkill, but I have some issues when the directories have spaces in their names.
The
$ find . -type d -print0 | while read -d $'\0' dir; do xxx; done
loops over all the subdirectories in this place, ignoring the white spaces (to some extend).
$ cd "$dir"; echo " process $dir"; cd -;
goes to the directory and back. It also prints some info to check the progress.
$ find . -maxdepth 1 -name "*.ogg.mp3" -exec rename 's/.ogg.mp3/.mp3/' {} \;
renames the file within the current directory.
The whole should work with directories and file names that include white spaces.
If you use the logfile feature of ddrescue, the data is rescued very efficiently (only the needed blocks are read). Also you can interrupt the rescue at any time and resume it later at the same point.
http://www.gnu.org/software/ddrescue/ddrescue.html
Capitalize first letter of each word in a string.
This command would be useful when it is desirable to list only the directories. 'egrep' chooses only the lines that begin with 'd'.
To take information about the characteristics of the installed memory modules.
My key is the anonymous one, is good for 50 post an hour with a maximun number of uploads a day, probably will run out, if that happend you can get a free key at the site.
Summarize established connections after netstat output.
Using tee and /dev/stderr you can send one command output to terminal before executing wc so you can summarize at the bottom of the output.