|By Hovhannes Avoyan||
|August 25, 2011 04:30 PM EDT||
In the first part of our series we described how to use find (and locate) to search for files using their names. Today we are going to review how to utilize find in a less common but very useful way. But first a few words on testing (okay, this might not be necessary for everyone, but bear with me!).
1. How to test
It is very important to remember that the find command allows you to create a list of objects having the value of a property the same, greater or smaller then given “n” — which stands for a number of days defined as 24 hours periods, with any frictional part ignored:
- +n – value of file property grater than n,
- n – value of file property the same as n,
- -n – value of file property smaller than n.
2. Search using time related information.
One of the most useful features of find is the ability to separate files based on the time of their creation, access and modification. This is done by the family of “time” tests. In “n” language, 47 hours will be given the same value as 25 hours (n=1). This behaviour can be changed by adding the option “-daystart” (measure time from beginning of today, so “n” for yesterday equals 1 in front of a test. Have a look at these time definitions below:
- -mtime n (Modification TIME) – probably the most useful from time-related tests, allowing to search files based on their modification time. If you want to have a list of all log files modified 2 days ago (or to be precise between 48 and 72 hours ago) you can run:
find /var/log -mtime 2
- -atime n (Access TIME) – the results based on a file’s last access time. If you want to see all logs accessed today you can run:
find /var/log -atime 0
Please remember it might be misleading if you check the file system mounted with option -noatime (which improves performance).
- -ctime n ([status] Change TIME) – this test searches files based on change of status (It means ownership, access privileges or type). For example you want to find which (or any at all) of the files in your home directory have changed status in the last 48 hours (which might indicate problems) you can run:
find ~ -ctime -1
Measuring time in days is not always very handy. Sometimes it is necessary to find more recent changes. To make it possible, the above test has minuets-base equivalents:
- -mmin n – test modification time but in minutes rather than days;
- -amin n – test access time but in minutes rather than days;
- -cmin n – test status change time but in minutes rather than days.
Imagine the following situation: You have downloaded a file under five minutes ago, but you are not sure where you have saved it. You can try the following command:
find ~ -mmin -5
In this scenario mmin can be change to amin or cmin, because all “three times” have the same initial value.
Lastly, there are tests allow you to search files in relation to a property of another file. For example:
- -newer file – returns files modified more recently than the given file,
- -anewer file – return files accessed more recently than the given file,
- -cnewer file – return files with the status changed more recently than for the given file.
For example, the following command will list all files accessed later than file DSCF1002.avi in directory /home/movies:
find /home/movies -anewer DSCF1002.avi
There is also a fourth ‘newer’ test:
- -newerXY reference – which compares timestamp with the given timestamp of the reference file. XY has to be substituted by one or two from the following timestamp type:
- a – access time,
- B – birth (creation) time,
- c – inode status change time,
- m – modification time,
- t – reference is interpreted directly as a time.
Please remember that not all combinations are supported (notable X cannot equal t) and B is not supported on all systems. For example, to get the list of all files accessed in /var/cache later than (in BST) July 20th 10:45:32 2011:
find /var/cache -newerat ‘Jul 20 10:45:32 BST 2011’
To create another list with files modified later than the last access to your .profile file:
find /var/cache -newerma ~/.profile
There is one more test that allows you to search based on a time-related parameter:
- -used n – creates the list of files accessed “n” days after its status was last changed. To find not very often accessed files (let say one month) in /var directory, use this command:
find /var/ -used +30
Appendix. ls and time
You can try to create similar lists with a little help from the ls command. There are three ls commands that correspond to the above find test. They allow you to sort files according to:
- -t – modification time (mtime);
- -u – access time (atime);
- -c – status change time (ctime).
Option -t simply sorts by modification time, but option -u and -c behave different in connection with other options:
- ls -u – sorts by access time (receptively ls -c sorts by status change time);
- ls -ul – shows access time but sorts by name (ls -cl – shows status change time but sorts by name);
- ls -ult – shows and sorts by access time (ls -clt – shows and sorts by status change time).
WebRTC has had a real tough three or four years, and so have those working with it. Only a few short years ago, the development world were excited about WebRTC and proclaiming how awesome it was. You might have played with the technology a couple of years ago, only to find the extra infrastructure requirements were painful to implement and poorly documented. This probably left a bitter taste in your mouth, especially when things went wrong.
Aug. 30, 2015 01:00 AM EDT Reads: 429
SYS-CON Events announced today that IceWarp will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. IceWarp, the leader of cloud and on-premise messaging, delivers secured email, chat, documents, conferencing and collaboration to today's mobile workforce, all in one unified interface
Aug. 30, 2015 01:00 AM EDT Reads: 384
With the proliferation of connected devices underpinning new Internet of Things systems, Brandon Schulz, Director of Luxoft IoT – Retail, will be looking at the transformation of the retail customer experience in brick and mortar stores in his session at @ThingsExpo. Questions he will address include: Will beacons drop to the wayside like QR codes, or be a proximity-based profit driver? How will the customer experience change in stores of all types when everything can be instrumented and analyzed? As an area of investment, how might a retail company move towards an innovation methodolo...
Aug. 29, 2015 11:45 PM EDT Reads: 430
The Internet of Things (IoT) is about the digitization of physical assets including sensors, devices, machines, gateways, and the network. It creates possibilities for significant value creation and new revenue generating business models via data democratization and ubiquitous analytics across IoT networks. The explosion of data in all forms in IoT requires a more robust and broader lens in order to enable smarter timely actions and better outcomes. Business operations become the key driver of IoT applications and projects. Business operations, IT, and data scientists need advanced analytics t...
Aug. 29, 2015 07:30 PM EDT Reads: 381
A producer of the first smartphones and tablets, presenter Lee M. Williams will talk about how he is now applying his experience in mobile technology to the design and development of the next generation of Environmental and Sustainability Services at ETwater. In his session at @ThingsExpo, Lee Williams, COO of ETwater, will talk about how he is now applying his experience in mobile technology to the design and development of the next generation of Environmental and Sustainability Services at ETwater.
Aug. 29, 2015 03:45 PM EDT Reads: 114
Consumer IoT applications provide data about the user that just doesn’t exist in traditional PC or mobile web applications. This rich data, or “context,” enables the highly personalized consumer experiences that characterize many consumer IoT apps. This same data is also providing brands with unprecedented insight into how their connected products are being used, while, at the same time, powering highly targeted engagement and marketing opportunities. In his session at @ThingsExpo, Nathan Treloar, President and COO of Bebaio, will explore examples of brands transforming their businesses by t...
Aug. 29, 2015 11:00 AM EDT Reads: 205
SYS-CON Events announced today that Pythian, a global IT services company specializing in helping companies leverage disruptive technologies to optimize revenue-generating systems, has been named “Bronze Sponsor” of SYS-CON's 17th Cloud Expo, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Founded in 1997, Pythian is a global IT services company that helps companies compete by adopting disruptive technologies such as cloud, Big Data, advanced analytics, and DevOps to advance innovation and increase agility. Specializing in designing, imple...
Aug. 29, 2015 11:00 AM EDT Reads: 256
While many app developers are comfortable building apps for the smartphone, there is a whole new world out there. In his session at @ThingsExpo, Narayan Sainaney, Co-founder and CTO of Mojio, will discuss how the business case for connected car apps is growing and, with open platform companies having already done the heavy lifting, there really is no barrier to entry.
Aug. 29, 2015 10:30 AM EDT Reads: 115
SYS-CON Events announced today that HPM Networks will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. For 20 years, HPM Networks has been integrating technology solutions that solve complex business challenges. HPM Networks has designed solutions for both SMB and enterprise customers throughout the San Francisco Bay Area.
Aug. 29, 2015 09:30 AM EDT Reads: 855
Through WebRTC, audio and video communications are being embedded more easily than ever into applications, helping carriers, enterprises and independent software vendors deliver greater functionality to their end users. With today’s business world increasingly focused on outcomes, users’ growing calls for ease of use, and businesses craving smarter, tighter integration, what’s the next step in delivering a richer, more immersive experience? That richer, more fully integrated experience comes about through a Communications Platform as a Service which allows for messaging, screen sharing, video...
Aug. 29, 2015 08:45 AM EDT Reads: 591
SYS-CON Events announced today that Micron Technology, Inc., a global leader in advanced semiconductor systems, will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Micron’s broad portfolio of high-performance memory technologies – including DRAM, NAND and NOR Flash – is the basis for solid state drives, modules, multichip packages and other system solutions. Backed by more than 35 years of technology leadership, Micron's memory solutions enable the world's most innovative computing, consumer,...
Aug. 29, 2015 08:45 AM EDT Reads: 203
As more intelligent IoT applications shift into gear, they’re merging into the ever-increasing traffic flow of the Internet. It won’t be long before we experience bottlenecks, as IoT traffic peaks during rush hours. Organizations that are unprepared will find themselves by the side of the road unable to cross back into the fast lane. As billions of new devices begin to communicate and exchange data – will your infrastructure be scalable enough to handle this new interconnected world?
Aug. 29, 2015 07:45 AM EDT Reads: 134
As more and more data is generated from a variety of connected devices, the need to get insights from this data and predict future behavior and trends is increasingly essential for businesses. Real-time stream processing is needed in a variety of different industries such as Manufacturing, Oil and Gas, Automobile, Finance, Online Retail, Smart Grids, and Healthcare. Azure Stream Analytics is a fully managed distributed stream computation service that provides low latency, scalable processing of streaming data in the cloud with an enterprise grade SLA. It features built-in integration with Azur...
Aug. 28, 2015 07:45 PM EDT Reads: 202
Too often with compelling new technologies market participants become overly enamored with that attractiveness of the technology and neglect underlying business drivers. This tendency, what some call the “newest shiny object syndrome,” is understandable given that virtually all of us are heavily engaged in technology. But it is also mistaken. Without concrete business cases driving its deployment, IoT, like many other technologies before it, will fade into obscurity.
Aug. 28, 2015 06:00 PM EDT Reads: 332
Akana has announced the availability of the new Akana Healthcare Solution. The API-driven solution helps healthcare organizations accelerate their transition to being secure, digitally interoperable businesses. It leverages the Health Level Seven International Fast Healthcare Interoperability Resources (HL7 FHIR) standard to enable broader business use of medical data. Akana developed the Healthcare Solution in response to healthcare businesses that want to increase electronic, multi-device access to health records while reducing operating costs and complying with government regulations.
Aug. 26, 2015 07:00 AM EDT Reads: 126
For IoT to grow as quickly as analyst firms’ project, a lot is going to fall on developers to quickly bring applications to market. But the lack of a standard development platform threatens to slow growth and make application development more time consuming and costly, much like we’ve seen in the mobile space. In his session at @ThingsExpo, Mike Weiner, Product Manager of the Omega DevCloud with KORE Telematics Inc., discussed the evolving requirements for developers as IoT matures and conducted a live demonstration of how quickly application development can happen when the need to comply wit...
Aug. 2, 2015 11:15 AM EDT Reads: 550
The Internet of Everything (IoE) brings together people, process, data and things to make networked connections more relevant and valuable than ever before – transforming information into knowledge and knowledge into wisdom. IoE creates new capabilities, richer experiences, and unprecedented opportunities to improve business and government operations, decision making and mission support capabilities.
Aug. 1, 2015 10:00 AM EDT Reads: 478
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at @ThingsExpo, James Kirkland, Red Hat's Chief Architect for the Internet of Things and Intelligent Systems, described how to revolutionize your archit...
Jul. 30, 2015 07:30 PM EDT Reads: 1,561
MuleSoft has announced the findings of its 2015 Connectivity Benchmark Report on the adoption and business impact of APIs. The findings suggest traditional businesses are quickly evolving into "composable enterprises" built out of hundreds of connected software services, applications and devices. Most are embracing the Internet of Things (IoT) and microservices technologies like Docker. A majority are integrating wearables, like smart watches, and more than half plan to generate revenue with APIs within the next year.
Jul. 30, 2015 02:30 PM EDT Reads: 278
Growth hacking is common for startups to make unheard-of progress in building their business. Career Hacks can help Geek Girls and those who support them (yes, that's you too, Dad!) to excel in this typically male-dominated world. Get ready to learn the facts: Is there a bias against women in the tech / developer communities? Why are women 50% of the workforce, but hold only 24% of the STEM or IT positions? Some beginnings of what to do about it! In her Opening Keynote at 16th Cloud Expo, Sandy Carter, IBM General Manager Cloud Ecosystem and Developers, and a Social Business Evangelist, d...
Jul. 30, 2015 12:00 PM EDT Reads: 2,223