bashoneliners.com

Explanation

The function expanded would look like this :

T() {
    if [[ "$2" =~ ${1}['/'?] ]] ; then
        echo "$2 is child of $1"
        return 0
    else
        echo "$2 is NOT child of $1 ($?)"
        return 1
    fi
}

Explanation

for img in /path/to/rawimages/*.RW2; do Loop through image directory

pfsin ${img} | read the raw image

pfssize -x 1024 -y 768 | resize it to 1024x768 because fattal looks better at low resolutions

pfstmo_fattal02 -v -s 1 | use the fattal tone mapping operator, be verbose and saturation value of 1

pfsout ./path/to/finished/${img%%}.jpg; done output and rename the file as a jpg.

Examples of fattal tone mapped images http://goo.gl/IayQQ

pfstools website http://pfstools.sourceforge.net/

Explanation

• uuencode /var/log/messages messages.txt -- the first parameter is the file to attach, the second is the filename to use for the attachment
• mailx -s subject emailaddress -- takes standard input as the content of the email

Explanation

Will calculate a md5sum from an input string

Wrap it up in a function:

function md5() { md5sum<<<$1 | cut -f1 -d' '; }

Example usage:

md5 "this is a long string test_string"

md5 singleWordExample

Explanation

Can come handy when you'd like to post a song to YT or somethin' :)

Can be easily wrapped up in a function:

function mp3tovidwithimg() { ffmpeg -loop_input -i $1 -i $2 -shortest -acodec copy $3; }

and used like that:

mp3tovidwithimg cover.jpeg music_track.mp3 output_vid.mp4

Explanation

Will find all of the distinct file extensions in a folder hierarchy.

Originally posted at: http://stackoverflow.com/questions/1842254/how-can-i-find-all-of-the-distinct-file-extensions-in-a-folder-hierarchy

Explanation

will dump the traffic into a file with a time-stamp in its name. Example filename:

dump-2013-05-17_15-46-UTC.pcap

Explanation

first get the process id of the chome browser process which runs the flashplayer export it to a variable to be used later. Then we get in subshell the filedescriptor which is marked deleted and construct the /proc path for the in memory fileimage and copy it to the file named saved.flv

Explanation

Suppose you have a backup directory with backup snapshots named by timestamp:

$ ls
2013-05-03-103022
2013-05-04-103033
2013-05-05-103023
2013-05-06-103040
2013-05-07-103022

You want to remove snapshots older than 3 days. The one-liner does it:

$ date
Tue May  7 13:50:57 KST 2013
$ ls | grep '....-..-..-......' | sort | xargs -I {} bash -c "[[ x{} < x$(date -d '3 days ago' +%Y-%m-%d-%H%M%S) ]] && rm -rfv {}"
removed directory: `2013-05-03-103022'
removed directory: `2013-05-04-103033'

Explanation

This one-liner initially does a recursive listing of the current directory: ls -R.

Any output other that the directory names, identified by ":" at the very end of each line (hence ":$"), is filtered out: grep ":$".

Finally there's a little of "sed" magic replacing any hierarchy level ("/") with dashes ("-"): sed ....

Works for me with Bash under Linux, Mac OS X, Solaris.

Explanation

This will remove the leading dot from all files in the current directory using mv, effectively "unhiding" them.

It will not affect subdirectories.

Explanation

using for, for looping the files through a directory and using bash build-in case modification expansion to upper case the files

Explanation

there is a lower/upper case modification build-in bash using for, for looping files through directory

Explanation

The command simply traverses the specified directory tree and for each file and directory it prints the UID of the owner, GID of the group, the permission bits and the path.

To compare file owners and permissions of two directory trees you can run this command for each directory, save the output in two files and then compare them using diff or similar.

See man find for more explanation of all the possible symbols you can use with -printf

Explanation

Shows latest file (by last modification of file status information) for the given pattern. So in this example filename = custlist*.xls.

We use ls to do the sorting (-t) and head to pick the top one. xargs is given the -r option so that ls isn't run if there is no match.

Explanation

eg.

file1:

123456
234567
345678

file2:

234567
345678
456789

We want only the uniq lines from each file:

result

123456
456789

Explanation

The purpose of the one-liner is to find the the "latest" version of the custlist_*.xls file from among multiple versions in directories and sub-directories, for example:

./c/custlist_v1.003.xls
./c/custlist_v2.001.xls
./d/b/custlist_v1.001.xls
./d/custlist_v1.002.xls

Let's decompose the one-liner to the big steps:

• find . -name custlist\* -- find the files matching the target pattern
• ... | perl -ne '...' -- run perl, with the input wrapped around in a while loop so that each line in the input is set in the variable $_
• $path = $_; s?.*/??; $name = $_; -- save the full path in $path, and cut off the subdirectory part to get to the base name of the file and save it in $name
• $map{$name} = $path; -- build a mapping of $name to $path
• ++$c; -- we count the elements, to use it later
• (sort(keys(%map)))[$c-1] -- sort the keys of the map, and get the last element, which is custlist_v2.001.xls in this example
• END { print $map{$last} }' -- at the end of all input data, print the path of the latest version of the file

Explanation

• convert is part of ImageMagick image manipulation tool
• -thumbnail x80 means create a thumbnail image of height 80 pixels, the width will be automatically chosen to make the image proportional
• The [0] is to create a thumbnail for the first page only, without that a thumbnail image would be created for each page in the pdf file

Explanation

zip does not have an explicit option to overwrite/recreate an existing zip file. If the specified destination file already exists, zip updates it. The problem is that files you did not specify to add to the zip but they already existed in the zip, will not be removed.

For example let's say you created a zip file from a directory with the command:

zip -r /path/to/out.zip /path/to/dir

Next you delete some files from the directory and repeat the command to recreate the zip. But that will not recreate the zip, it will only update it, and so the file you deleted from the directory will still be there in the zip.

One way to recreate the zip is to delete the file first. Another, better way is to use the --filesync or -FS flag. With this flag zip will remove files from the zip that do not exist anymore in the filesystem. This is more efficient than recreating the zip.

Explanation

Using sed to remove a specific line

Adding -i parameter for inplace editing

Explanation

Using two for loop to create second & third block of IP and finally through a formatted seq to printf the output

More efficient/using less memory than using {..} (range)

Explanation

In short, it runs a Python one-line script which imports the 'os' module and uses it to get the load average. It then indexes into a tuple, using the index of zero. The tuple is like this: (oneminuteaverage, fiveminuteaverage, fifteenminuteaverage), so you could substitute 0 for 1 to get the five minute load average, or 2 to get the fifteen minute load average. I find this really useful when writing larger bash one-liners which require this information, as I don't have to parse the output of uptime.

Explanation

A slightly improved version of the original one-liner to allow negative indexes to extract columns relative to the end of the line, for example:

$ echo a b c | col 1 -0 -1
a c b

In this example the function expands to:

awk '{print $(1), $(NF-0), $(NF-1)}'

Explanation

Basically, it sends DD the USR1 signal, displaying status, every 5 seconds. It runs watch at an interval of 5, killing dd with -USR1. If you're running DD as root you'll have to run this as root.

Explanation

The time builtin prints a summary of the real time, user CPU time and system CPU time spent executing commands, for example:

$ time sleep 1

real    0m1.002s
user    0m0.000s
sys     0m0.002s

If you need to parse this output, it helps to simplify it using the TIMEFORMAT variable. The value %R means "the elapsed time in seconds", for example:

$ TIMEFORMAT=%R
$ time sleep 1
1.004

The complete documentation of the format definition is in man bash, search for TIMEFORMAT.