34 skills found · Page 1 of 2
AndreaCensi / ContractsPyContracts is a Python package that allows to declare constraints on function parameters and return values. Contracts can be specified using Python3 annotations, or inside a docstring. PyContracts supports a basic type system, variables binding, arithmetic constraints, and has several specialized contracts and an extension API.
Yinzo / Reprinta Python 2/3 module for binding variables and refreshing multi-line output in terminal.
sanusanth / Python Basic ProgramsWhat is Python? Executive Summary Python is an interpreted, object-oriented, high-level programming language with dynamic semantics. Its high-level built in data structures, combined with dynamic typing and dynamic binding, make it very attractive for Rapid Application Development, as well as for use as a scripting or glue language to connect existing components together. Python's simple, easy to learn syntax emphasizes readability and therefore reduces the cost of program maintenance. Python supports modules and packages, which encourages program modularity and code reuse. The Python interpreter and the extensive standard library are available in source or binary form without charge for all major platforms, and can be freely distributed. Often, programmers fall in love with Python because of the increased productivity it provides. Since there is no compilation step, the edit-test-debug cycle is incredibly fast. Debugging Python programs is easy: a bug or bad input will never cause a segmentation fault. Instead, when the interpreter discovers an error, it raises an exception. When the program doesn't catch the exception, the interpreter prints a stack trace. A source level debugger allows inspection of local and global variables, evaluation of arbitrary expressions, setting breakpoints, stepping through the code a line at a time, and so on. The debugger is written in Python itself, testifying to Python's introspective power. On the other hand, often the quickest way to debug a program is to add a few print statements to the source: the fast edit-test-debug cycle makes this simple approach very effective. What is Python? Python is a popular programming language. It was created by Guido van Rossum, and released in 1991. It is used for: web development (server-side), software development, mathematics, system scripting. What can Python do? Python can be used on a server to create web applications. Python can be used alongside software to create workflows. Python can connect to database systems. It can also read and modify files. Python can be used to handle big data and perform complex mathematics. Python can be used for rapid prototyping, or for production-ready software development. Why Python? Python works on different platforms (Windows, Mac, Linux, Raspberry Pi, etc). Python has a simple syntax similar to the English language. Python has syntax that allows developers to write programs with fewer lines than some other programming languages. Python runs on an interpreter system, meaning that code can be executed as soon as it is written. This means that prototyping can be very quick. Python can be treated in a procedural way, an object-oriented way or a functional way. Good to know The most recent major version of Python is Python 3, which we shall be using in this tutorial. However, Python 2, although not being updated with anything other than security updates, is still quite popular. In this tutorial Python will be written in a text editor. It is possible to write Python in an Integrated Development Environment, such as Thonny, Pycharm, Netbeans or Eclipse which are particularly useful when managing larger collections of Python files. Python Syntax compared to other programming languages Python was designed for readability, and has some similarities to the English language with influence from mathematics. Python uses new lines to complete a command, as opposed to other programming languages which often use semicolons or parentheses. Python relies on indentation, using whitespace, to define scope; such as the scope of loops, functions and classes. Other programming languages often use curly-brackets for this purpose. Applications for Python Python is used in many application domains. Here's a sampling. The Python Package Index lists thousands of third party modules for Python. Web and Internet Development Python offers many choices for web development: Frameworks such as Django and Pyramid. Micro-frameworks such as Flask and Bottle. Advanced content management systems such as Plone and django CMS. Python's standard library supports many Internet protocols: HTML and XML JSON E-mail processing. Support for FTP, IMAP, and other Internet protocols. Easy-to-use socket interface. And the Package Index has yet more libraries: Requests, a powerful HTTP client library. Beautiful Soup, an HTML parser that can handle all sorts of oddball HTML. Feedparser for parsing RSS/Atom feeds. Paramiko, implementing the SSH2 protocol. Twisted Python, a framework for asynchronous network programming. Scientific and Numeric Python is widely used in scientific and numeric computing: SciPy is a collection of packages for mathematics, science, and engineering. Pandas is a data analysis and modeling library. IPython is a powerful interactive shell that features easy editing and recording of a work session, and supports visualizations and parallel computing. The Software Carpentry Course teaches basic skills for scientific computing, running bootcamps and providing open-access teaching materials. Education Python is a superb language for teaching programming, both at the introductory level and in more advanced courses. Books such as How to Think Like a Computer Scientist, Python Programming: An Introduction to Computer Science, and Practical Programming. The Education Special Interest Group is a good place to discuss teaching issues. Desktop GUIs The Tk GUI library is included with most binary distributions of Python. Some toolkits that are usable on several platforms are available separately: wxWidgets Kivy, for writing multitouch applications. Qt via pyqt or pyside Platform-specific toolkits are also available: GTK+ Microsoft Foundation Classes through the win32 extensions Software Development Python is often used as a support language for software developers, for build control and management, testing, and in many other ways. SCons for build control. Buildbot and Apache Gump for automated continuous compilation and testing. Roundup or Trac for bug tracking and project management. Business Applications Python is also used to build ERP and e-commerce systems: Odoo is an all-in-one management software that offers a range of business applications that form a complete suite of enterprise management applications. Try ton is a three-tier high-level general purpose application platform.
eee-c / Angular Bind PolymerAngular directive for *double* variable binding of Polymer attributes.
IGlab-VUMC / MAGE Ab GenerationMonoclonal Antibody GEnerator (MAGE) - a fine-tuned LLM for generating paired heavy-light antibody variable sequences with predicted binding specificity to an input antigen prompt sequence
brendanzab / MonikerAutomagical variable binding library for Rust
rocq-community / AutosubstAutomation for de Bruijn syntax and substitution in Coq [maintainers=@RalfJung,@co-dan]
SOYJUN / FTP Implement Based On UDPThe aim of this assignment is to have you do UDP socket client / server programming with a focus on two broad aspects : Setting up the exchange between the client and server in a secure way despite the lack of a formal connection (as in TCP) between the two, so that ‘outsider’ UDP datagrams (broadcast, multicast, unicast - fortuitously or maliciously) cannot intrude on the communication. Introducing application-layer protocol data-transmission reliability, flow control and congestion control in the client and server using TCP-like ARQ sliding window mechanisms. The second item above is much more of a challenge to implement than the first, though neither is particularly trivial. But they are not tightly interdependent; each can be worked on separately at first and then integrated together at a later stage. Apart from the material in Chapters 8, 14 & 22 (especially Sections 22.5 - 22.7), and the experience you gained from the preceding assignment, you will also need to refer to the following : ioctl function (Chapter 17). get_ifi_info function (Section 17.6, Chapter 17). This function will be used by the server code to discover its node’s network interfaces so that it can bind all its interface IP addresses (see Section 22.6). ‘Race’ conditions (Section 20.5, Chapter 20) You also need a thorough understanding of how the TCP protocol implements reliable data transfer, flow control and congestion control. Chapters 17- 24 of TCP/IP Illustrated, Volume 1 by W. Richard Stevens gives a good overview of TCP. Though somewhat dated for some things (it was published in 1994), it remains, overall, a good basic reference. Overview This assignment asks you to implement a primitive file transfer protocol for Unix platforms, based on UDP, and with TCP-like reliability added to the transfer operation using timeouts and sliding-window mechanisms, and implementing flow and congestion control. The server is a concurrent server which can handle multiple clients simultaneously. A client gives the server the name of a file. The server forks off a child which reads directly from the file and transfers the contents over to the client using UDP datagrams. The client prints out the file contents as they come in, in order, with nothing missing and with no duplication of content, directly on to stdout (via the receiver sliding window, of course, but with no other intermediate buffering). The file to be transferred can be of arbitrary length, but its contents are always straightforward ascii text. As an aside let me mention that assuming the file contents ascii is not as restrictive as it sounds. We can always pretend, for example, that binary files are base64 encoded (“ASCII armor”). A real file transfer protocol would, of course, have to worry about transferring files between heterogeneous platforms with different file structure conventions and semantics. The sender would first have to transform the file into a platform-independent, protocol-defined, format (using, say, ASN.1, or some such standard), and the receiver would have to transform the received file into its platform’s native file format. This kind of thing can be fairly time consuming, and is certainly very tedious, to implement, with little educational value - it is not part of this assignment. Arguments for the server You should provide the server with an input file server.in from which it reads the following information, in the order shown, one item per line : Well-known port number for server. Maximum sending sliding-window size (in datagram units). You will not be handing in your server.in file. We shall create our own when we come to test your code. So it is important that you stick strictly to the file name and content conventions specified above. The same applies to the client.in input file below. Arguments for the client The client is to be provided with an input file client.in from which it reads the following information, in the order shown, one item per line : IP address of server (not the hostname). Well-known port number of server. filename to be transferred. Receiving sliding-window size (in datagram units). Random generator seed value. Probability p of datagram loss. This should be a real number in the range [ 0.0 , 1.0 ] (value 0.0 means no loss occurs; value 1.0 means all datagrams all lost). The mean µ, in milliseconds, for an exponential distribution controlling the rate at which the client reads received datagram payloads from its receive buffer. Operation Server starts up and reads its arguments from file server.in. As we shall see, when a client communicates with the server, the server will want to know what IP address that client is using to identify the server (i.e. , the destination IP address in the incoming datagram). Normally, this can be done relatively straightforwardly using the IP_RECVDESTADDR socket option, and picking up the information using the ancillary data (‘control information’) capability of the recvmsg function. Unfortunately, Solaris 2.10 does not support the IP_RECVDESTADDR option (nor, incidentally, does it support the msg_flags option in msghdr - see p.390). This considerably complicates things. In the absence of IP_RECVDESTADDR, what the server has to do as part of its initialization phase is to bind each IP address it has (and, simultaneously, its well-known port number, which it has read in from server.in) to a separate UDP socket. The code in Section 22.6, which uses the get_ifi_info function, shows you how to do that. However, there are important differences between that code and the version you want to implement. The code of Section 22.6 binds the IP addresses and forks off a child for each address that is bound to. We do not want to do that. Instead you should have an array of socket descriptors. For each IP address, create a new socket and bind the address (and well-known port number) to the socket without forking off child processes. Creating child processes comes later, when clients arrive. The code of Section 22.6 also attempts to bind broadcast addresses. We do not want to do this. It binds a wildcard IP address, which we certainly do not want to do either. We should bind strictly only unicast addresses (including the loopback address). The get_ifi_info function (which the code in Section 22.6 uses) has to be modified so that it also gets the network masks for the IP addresses of the node, and adds these to the information stored in the linked list of ifi_info structures (see Figure 17.5, p.471) it produces. As you go binding each IP address to a distinct socket, it will be useful for later processing to build your own array of structures, where a structure element records the following information for each socket : sockfd IP address bound to the socket network mask for the IP address subnet address (obtained by doing a bit-wise and between the IP address and its network mask) Report, in a ReadMe file which you hand in with your code, on the modifications you had to introduce to ensure that only unicast addresses are bound, and on your implementation of the array of structures described above. You should print out on stdout, with an appropriate message and appropriately formatted in dotted decimal notation, the IP address, network mask, and subnet address for each socket in your array of structures (you do not need to print the sockfd). The server now uses select to monitor the sockets it has created for incoming datagrams. When it returns from select, it must use recvfrom or recvmsg to read the incoming datagram (see 6. below). When a client starts, it first reads its arguments from the file client.in. The client checks if the server host is ‘local’ to its (extended) Ethernet. If so, all its communication to the server is to occur as MSG_DONTROUTE (or SO_DONTROUTE socket option). It determines if the server host is ‘local’ as follows. The first thing the client should do is to use the modified get_ifi_info function to obtain all of its IP addresses and associated network masks. Print out on stdout, in dotted decimal notation and with an appropriate message, the IP addresses and network masks obtained. In the following, IPserver designates the IP address the client will use to identify the server, and IPclient designates the IP address the client will choose to identify itself. The client checks whether the server is on the same host. If so, it should use the loopback address 127.0.0.1 for the server (i.e. , IPserver = 127.0.0.1). IPclient should also be set to the loopback address. Otherwise it proceeds as follows: IPserver is set to the IP address for the server in the client.in file. Given IPserver and the (unicast) IP addresses and network masks for the client returned by get_ifi_info in the linked list of ifi_info structures, you should be able to figure out if the server node is ‘local’ or not. This will be discussed in class; but let me just remind you here that you should use ‘longest prefix matching’ where applicable. If there are multiple client addresses, and the server host is ‘local’, the client chooses an IP address for itself, IPclient, which matches up as ‘local’ according to your examination above. If the server host is not ‘local’, then IPclient can be chosen arbitrarily. Print out on stdout the results of your examination, as to whether the server host is ‘local’ or not, as well as the IPclient and IPserver addresses selected. Note that this manner of determining whether the server is local or not is somewhat clumsy and ‘over-engineered’, and, as such, should be viewed more in the nature of a pedagogical exercise. Ideally, we would like to look up the server IP address(es) in the routing table (see Section 18.3). This requires that a routing socket be created, for which we need superuser privilege. Alternatively, we might want to dump out the routing table, using the sysctl function for example (see Section 18.4), and examine it directly. Unfortunately, Solaris 2.10 does not support sysctl. Furthermore, note that there is a slight problem with the address 130.245.1.123/24 assigned to compserv3 (see rightmost column of file hosts, and note that this particular compserv3 address “overlaps” with the 130.245.1.x/28 addresses in that same column assigned to compserv1, compserv2 & comserv4). In particular, if the client is running on compserv3 and the server on any of the other three compservs, and if that server node is also being identified to the client by its /28 (rather than its /24) address, then the client will get a “false positive” when it tests as to whether the server node is local or not. In other words, the client will deem the server node to be local, whereas in fact it should not be considered local. Because of this, it is perhaps best simply not to use compserv3 to run the client (but it is o.k. to use it to run the server). Finally, using MSG_DONTROUTE where possible would seem to gain us efficiency, in as much as the kernel does not need to consult the routing table for every datagram sent. But, in fact, that is not so. Recall that one effect of connect with UDP sockets is that routing information is obtained by the kernel at the time the connect is issued. That information is cached and used for subsequent sends from the connected socket (see p.255). The client now creates a UDP socket and calls bind on IPclient, with 0 as the port number. This will cause the kernel to bind an ephemeral port to the socket. After the bind, use the getsockname function (Section 4.10) to obtain IPclient and the ephemeral port number that has been assigned to the socket, and print that information out on stdout, with an appropriate message and appropriately formatted. The client connects its socket to IPserver and the well-known port number of the server. After the connect, use the getpeername function (Section 4.10) to obtain IPserver and the well-known port number of the server, and print that information out on stdout, with an appropriate message and appropriately formatted. The client sends a datagram to the server giving the filename for the transfer. This send needs to be backed up by a timeout in case the datagram is lost. Note that the incoming datagram from the client will be delivered to the server at the socket to which the destination IP address that the datagram is carrying has been bound. Thus, the server can obtain that address (it is, of course, IPserver) and thereby achieve what IP_RECVDESTADDR would have given us had it been available. Furthermore, the server process can obtain the IP address (this will, of course, be IPclient) and ephemeral port number of the client through the recvfrom or recvmsg functions. The server forks off a child process to handle the client. The server parent process goes back to the select to listen for new clients. Hereafter, and unless otherwise stated, whenever we refer to the ‘server’, we mean the server child process handling the client’s file transfer, not the server parent process. Typically, the first thing the server child would be expected to do is to close all sockets it ‘inherits’ from its parent. However, this is not the case with us. The server child does indeed close the sockets it inherited, but not the socket on which the client request arrived. It leaves that socket open for now. Call this socket the ‘listening’ socket. The server (child) then checks if the client host is local to its (extended) Ethernet. If so, all its communication to the client is to occur as MSG_DONTROUTE (or SO_DONTROUTE socket option). If IPserver (obtained in 5. above) is the loopback address, then we are done. Otherwise, the server has to proceed with the following step. Use the array of structures you built in 1. above, together with the addresses IPserver and IPclient to determine if the client is ‘local’. Print out on stdout the results of your examination, as to whether the client host is ‘local’ or not. The server (child) creates a UDP socket to handle file transfer to the client. Call this socket the ‘connection’ socket. It binds the socket to IPserver, with port number 0 so that its kernel assigns an ephemeral port. After the bind, use the getsockname function (Section 4.10) to obtain IPserver and the ephemeral port number that has been assigned to the socket, and print that information out on stdout, with an appropriate message and appropriately formatted. The server then connects this ‘connection’ socket to the client’s IPclient and ephemeral port number. The server now sends the client a datagram, in which it passes it the ephemeral port number of its ‘connection’ socket as the data payload of the datagram. This datagram is sent using the ‘listening’ socket inherited from its parent, otherwise the client (whose socket is connected to the server’s ‘listening’ socket at the latter’s well-known port number) will reject it. This datagram must be backed up by the ARQ mechanism, and retransmitted in the event of loss. Note that if this datagram is indeed lost, the client might well time out and retransmit its original request message (the one carrying the file name). In this event, you must somehow ensure that the parent server does not mistake this retransmitted request for a new client coming in, and spawn off yet another child to handle it. How do you do that? It is potentially more involved than it might seem. I will be discussing this in class, as well as ‘race’ conditions that could potentially arise, depending on how you code the mechanisms I present. When the client receives the datagram carrying the ephemeral port number of the server’s ‘connection’ socket, it reconnects its socket to the server’s ‘connection’ socket, using IPserver and the ephemeral port number received in the datagram (see p.254). It now uses this reconnected socket to send the server an acknowledgment. Note that this implies that, in the event of the server timing out, it should retransmit two copies of its ‘ephemeral port number’ message, one on its ‘listening’ socket and the other on its ‘connection’ socket (why?). When the server receives the acknowledgment, it closes the ‘listening’ socket it inherited from its parent. The server can now commence the file transfer through its ‘connection’ socket. The net effect of all these binds and connects at server and client is that no ‘outsider’ UDP datagram (broadcast, multicast, unicast - fortuitously or maliciously) can now intrude on the communication between server and client. Starting with the first datagram sent out, the client behaves as follows. Whenever a datagram arrives, or an ACK is about to be sent out (or, indeed, the initial datagram to the server giving the filename for the transfer), the client uses some random number generator function random() (initialized by the client.in argument value seed) to decide with probability p (another client.in argument value) if the datagram or ACK should be discarded by way of simulating transmission loss across the network. (I will briefly discuss in class how you do this.) Adding reliability to UDP The mechanisms you are to implement are based on TCP Reno. These include : Reliable data transmission using ARQ sliding-windows, with Fast Retransmit. Flow control via receiver window advertisements. Congestion control that implements : SlowStart Congestion Avoidance (‘Additive-Increase/Multiplicative Decrease’ – AIMD) Fast Recovery (but without the window-inflation aspect of Fast Recovery) Only some, and by no means all, of the details for these are covered below. The rest will be presented in class, especially those concerning flow control and TCP Reno’s congestion control mechanisms in general : Slow Start, Congestion Avoidance, Fast Retransmit and Fast Recovery. Implement a timeout mechanism on the sender (server) side. This is available to you from Stevens, Section 22.5 . Note, however, that you will need to modify the basic driving mechanism of Figure 22.7 appropriately since the situation at the sender side is not a repetitive cycle of send-receive, but rather a straightforward progression of send-send-send-send- . . . . . . . . . . . Also, modify the RTT and RTO mechanisms of Section 22.5 as specified below. I will be discussing the details of these modifications and the reasons for them in class. Modify function rtt_stop (Fig. 22.13) so that it uses integer arithmetic rather than floating point. This will entail your also having to modify some of the variable and function parameter declarations throughout Section 22.5 from float to int, as appropriate. In the unprrt.h header file (Fig. 22.10) set : RTT_RXTMIN to 1000 msec. (1 sec. instead of the current value 3 sec.) RTT_RXTMAX to 3000 msec. (3 sec. instead of the current value 60 sec.) RTT_MAXNREXMT to 12 (instead of the current value 3) In function rtt_timeout (Fig. 22.14), after doubling the RTO in line 86, pass its value through the function rtt_minmax of Fig. 22.11 (somewhat along the lines of what is done in line 77 of rtt_stop, Fig. 22.13). Finally, note that with the modification to integer calculation of the smoothed RTT and its variation, and given the small RTT values you will experience on the cs / sbpub network, these calculations should probably now be done on a millisecond or even microsecond scale (rather than in seconds, as is the case with Stevens’ code). Otherwise, small measured RTTs could show up as 0 on a scale of seconds, yielding a negative result when we subtract the smoothed RTT from the measured RTT (line 72 of rtt_stop, Fig. 22.13). Report the details of your modifications to the code of Section 22.5 in the ReadMe file which you hand in with your code. We need to have a sender sliding window mechanism for the retransmission of lost datagrams; and a receiver sliding window in order to ensure correct sequencing of received file contents, and some measure of flow control. You should implement something based on TCP Reno’s mechanisms, with cumulative acknowledgments, receiver window advertisements, and a congestion control mechanism I will explain in detail in class. For a reference on TCP’s mechanisms generally, see W. Richard Stevens, TCP/IP Illustrated, Volume 1 , especially Sections 20.2 - 20.4 of Chapter 20 , and Sections 21.1 - 21.8 of Chapter 21 . Bear in mind that our sequence numbers should count datagrams, not bytes as in TCP. Remember that the sender and receiver window sizes have to be set according to the argument values in client.in and server.in, respectively. Whenever the sender window becomes full and so ‘locks’, the server should print out a message to that effect on stdout. Similarly, whenever the receiver window ‘locks’, the client should print out a message on stdout. Be aware of the potential for deadlock when the receiver window ‘locks’. This situation is handled by having the receiver process send a duplicate ACK which acts as a window update when its window opens again (see Figure 20.3 and the discussion about it in TCP/IP Illustrated). However, this is not enough, because ACKs are not backed up by a timeout mechanism in the event they are lost. So we will also need to implement a persist timer driving window probes in the sender process (see Sections 22.1 & 22.2 in Chapter 22 of TCP/IP Illustrated). Note that you do not have to worry about the Silly Window Syndrome discussed in Section 22.3 of TCP/IP Illustrated since the receiver process consumes ‘full sized’ 512-byte messages from the receiver buffer (see 3. below). Report on the details of the ARQ mechanism you implemented in the ReadMe file you hand in. Indeed, you should report on all the TCP mechanisms you implemented in the ReadMe file, both the ones discussed here, and the ones I will be discussing in class. Make your datagram payload a fixed 512 bytes, inclusive of the file transfer protocol header (which must, at the very least, carry: the sequence number of the datagram; ACKs; and advertised window notifications). The client reads the file contents in its receive buffer and prints them out on stdout using a separate thread. This thread sits in a repetitive loop till all the file contents have been printed out, doing the following. It samples from an exponential distribution with mean µ milliseconds (read from the client.in file), sleeps for that number of milliseconds; wakes up to read and print all in-order file contents available in the receive buffer at that point; samples again from the exponential distribution; sleeps; and so on. The formula -1 × µ × ln( random( ) ) , where ln is the natural logarithm, yields variates from an exponential distribution with mean µ, based on the uniformly-distributed variates over ( 0 , 1 ) returned by random(). Note that you will need to implement some sort of mutual exclusion/semaphore mechanism on the client side so that the thread that sleeps and wakes up to consume from the receive buffer is not updating the state variables of the buffer at the same time as the main thread reading from the socket and depositing into the buffer is doing the same. Furthermore, we need to ensure that the main thread does not effectively monopolize the semaphore (and thus lock out for prolonged periods of time) the sleeping thread when the latter wakes up. See the textbook, Section 26.7, ‘Mutexes: Mutual Exclusion’, pp.697-701. You might also find Section 26.8, ‘Condition Variables’, pp.701-705, useful. You will need to devise some way by which the sender can notify the receiver when it has sent the last datagram of the file transfer, without the receiver mistaking that EOF marker as part of the file contents. (Also, note that the last data segment could be a “short” segment of less than 512 bytes – your client needs to be able to handle this correctly somehow.) When the sender receives an ACK for the last datagram of the transfer, the (child) server terminates. The parent server has to take care of cleaning up zombie children. Note that if we want a clean closing, the client process cannot simply terminate when the receiver ACKs the last datagram. This ACK could be lost, which would leave the (child) server process ‘hanging’, timing out, and retransmitting the last datagram. TCP attempts to deal with this problem by means of the TIME_WAIT state. You should have your receiver process behave similarly, sticking around in something akin to a TIME_WAIT state in case in case it needs to retransmit the ACK. In the ReadMe file you hand in, report on how you dealt with the issues raised here: sender notifying receiver of the last datagram, clean closing, and so on. Output Some of the output required from your program has been described in the section Operation above. I expect you to provide further output – clear, well-structured, well-laid-out, concise but sufficient and helpful – in the client and server windows by means of which we can trace the correct evolution of your TCP’s behaviour in all its intricacies : information (e.g., sequence number) on datagrams and acks sent and dropped, window advertisements, datagram retransmissions (and why : dup acks or RTO); entering/exiting Slow Start and Congestion Avoidance, ssthresh and cwnd values; sender and receiver windows locking/unlocking; etc., etc. . . . . The onus is on you to convince us that the TCP mechanisms you implemented are working correctly. Too many students do not put sufficient thought, creative imagination, time or effort into this. It is not the TA’s nor my responsibility to sit staring at an essentially blank screen, trying to summon up our paranormal psychology skills to figure out if your TCP implementation is really working correctly in all its very intricate aspects, simply because the transferred file seems to be printing o.k. in the client window. Nor is it our responsibility to strain our eyes and our patience wading through a mountain of obscure, ill-structured, hyper-messy, debugging-style output because, for example, your effort-conserving concept of what is ‘suitable’ is to dump your debugging output on us, relevant, irrelevant, and everything in between.
lambdageek / Unbound GenericsSpecify variable binding in syntax trees using GHC.Generics (reimplementation of Unbound)
thefrontside / Ember LetCreate variable bindings inside your handlebars templates
rocq-community / DblibCoq library for working with de Bruijn indices [maintainer=@KevOrr]
sweirich / Rebound# A simple variable binding library based on well-scoped indices and environments
phoe / Binding ArrowsAn implementation of threading macros based on binding anonymous variables.
dunnl / TealeavesA Coq library for abstract syntactical reasoning
Ch-Jad / CH JaDi Rajput1# Cmder [](https://gitter.im/cmderdev/cmder?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [](https://ci.appveyor.com/project/MartiUK/cmder) Cmder is a **software package** created out of pure frustration over absence of usable console emulator on Windows. It is based on [ConEmu](https://conemu.github.io/) with *major* config overhaul, comes with a Monokai color scheme, amazing [clink](https://chrisant996.github.io/clink/) (further enhanced by [clink-completions](https://github.com/vladimir-kotikov/clink-completions)) and a custom prompt layout.  ## Why use it The main advantage of Cmder is portability. It is designed to be totally self-contained with no external dependencies, which makes it great for **USB Sticks** or **cloud storage**. So you can carry your console, aliases and binaries (like wget, curl and git) with you anywhere. The Cmder's user interface is also designed to be more eye pleasing, and you can compare the main differences between Cmder and ConEmu [here](https://conemu.github.io/en/cmder.html). ## Installation ### Single User Portable Config 1. Download the [latest release](https://github.com/cmderdev/cmder/releases/) 2. Extract the archive. *Note: This path should not be `C:\Program Files` or anywhere else that would require Administrator access for modifying configuration files* 3. (optional) Place your own executable files into the `%cmder_root%\bin` folder to be injected into your PATH. 4. Run `Cmder.exe` ### Shared Cmder install with Non-Portable Individual User Config 1. Download the [latest release](https://github.com/cmderdev/cmder/releases/) 2. Extract the archive to a shared location. 3. (optional) Place your own executable files and custom app folders into the `%cmder_root%\bin`. See: [bin/README.md](./bin/Readme.md) - This folder to be injected into your PATH by default. - See `/max_depth [1-5]` in 'Command Line Arguments for `init.bat`' table to add subdirectories recursively. 4. (optional) Place your own custom app folders into the `%cmder_root%\opt`. See: [opt/README.md](./opt/Readme.md) - This folder will NOT be injected into your PATH so you have total control of what gets added. 5. Run `Cmder.exe` with `/C` command line argument. Example: `cmder.exe /C %userprofile%\cmder_config` * This will create the following directory structure if it is missing. ``` c:\users\[CH JaDi Rajput]\cmder_config ├───bin ├───config │ └───profile.d └───opt ``` - (optional) Place your own executable files and custom app folders into `%userprofile%\cmder_config\bin`. - This folder to be injected into your PATH by default. - See `/max_depth [1-5]` in 'Command Line Arguments for `init.bat`' table to add subdirectories recursively. - (optional) Place your own custom app folders into the `%user_profile%\cmder_config\opt`. - This folder will NOT be injected into your PATH so you have total control of what gets added. * Both the shared install and the individual user config locations can contain a full set of init and profile.d scripts enabling shared config with user overrides. See below. ## Cmder.exe Command Line Arguments | Argument | Description | | ------------------- | ----------------------------------------------------------------------- | | `/C [user_root_path]` | Individual user Cmder root folder. Example: `%userprofile%\cmder_config` | | `/M` | Use `conemu-%computername%.xml` for ConEmu settings storage instead of `user_conemu.xml` | | `/REGISTER [ALL, USER]` | Register a Windows Shell Menu shortcut. | | `/UNREGISTER [ALL, USER]` | Un-register a Windows Shell Menu shortcut. | | `/SINGLE` | Start Cmder in single mode. | | `/START [start_path]` | Folder path to start in. | | `/TASK [task_name]` | Task to start after launch. | | `/X [ConEmu extras pars]` | Forwards parameters to ConEmu | ## Context Menu Integration So you've experimented with Cmder a little and want to give it a shot in a more permanent home; ### Shortcut to open Cmder in a chosen folder 1. Open a terminal as an Administrator 2. Navigate to the directory you have placed Cmder 3. Execute `.\cmder.exe /REGISTER ALL` _If you get a message "Access Denied" ensure you are executing the command in an **Administrator** prompt._ In a file explorer window right click in or on a directory to see "Cmder Here" in the context menu. ## Keyboard shortcuts ### Tab manipulation * <kbd>Ctrl</kbd> + <kbd>T</kbd> : New tab dialog (maybe you want to open cmd as admin?) * <kbd>Ctrl</kbd> + <kbd>W</kbd> : Close tab * <kbd>Ctrl</kbd> + <kbd>D</kbd> : Close tab (if pressed on empty command) * <kbd>Shift</kbd> + <kbd>Alt</kbd> + <kbd>#Number</kbd> : Fast new tab: <kbd>1</kbd> - CMD, <kbd>2</kbd> - PowerShell * <kbd>Ctrl</kbd> + <kbd>Tab</kbd> : Switch to next tab * <kbd>Ctrl</kbd> + <kbd>Shift</kbd> + <kbd>Tab</kbd> : Switch to previous tab * <kbd>Ctrl</kbd> + <kbd>#Number</kbd> : Switch to tab #Number * <kbd>Alt</kbd> + <kbd>Enter</kbd>: Fullscreen ### Shell * <kbd>Ctrl</kbd> + <kbd>Alt</kbd> + <kbd>U</kbd> : Traverse up in directory structure (lovely feature!) * <kbd>End</kbd>, <kbd>Home</kbd>, <kbd>Ctrl</kbd> : Traversing text with as usual on Windows * <kbd>Ctrl</kbd> + <kbd>R</kbd> : History search * <kbd>Shift</kbd> + Mouse : Select and copy text from buffer _(Some shortcuts are not yet documented, though they exist - please document them here)_ ## Features ### Access to multiple shells in one window using tabs You can open multiple tabs each containing one of the following shells: | Task | Shell | Description | | ---- | ----- | ----------- | | Cmder | `cmd.exe` | Windows `cmd.exe` shell enhanced with Git, Git aware prompt, Clink (GNU Readline), and Aliases. | | Cmder as Admin | `cmd.exe` | Administrative Windows `cmd.exe` Cmder shell. | | PowerShell | `powershell.exe` | Windows PowerShell enhanced with Git and Git aware prompt . | | PowerShell as Admin | `powershell.exe` | Administrative Windows `powershell.exe` Cmder shell. | | Bash | `bash.exe` | Unix/Linux like bash shell running on Windows. | | Bash as Admin | `bash.exe` | Administrative Unix/Linux like bash shell running on Windows. | | Mintty | `bash.exe` | Unix/Linux like bash shell running on Windows. See below for Mintty configuration differences | | Mintty as Admin | `bash.exe` | Administrative Unix/Linux like bash shell running on Windows. See below for Mintty configuration differences | Cmder, PowerShell, and Bash tabs all run on top of the Windows Console API and work as you might expect in Cmder with access to use ConEmu's color schemes, key bindings and other settings defined in the ConEmu Settings dialog. ⚠ *NOTE:* Only the full edition of Cmder comes with a pre-installed bash, using a vendored [git-for-windows](https://gitforwindows.org/) installation. The pre-configured Bash tabs may not work on Cmder mini edition without additional configuration. You may however, choose to use an external installation of bash, such as Microsoft's [Subsystem for Linux](https://docs.microsoft.com/en-us/windows/wsl/install-win10) (called WSL) or the [Cygwin](https://cygwin.com/) project which provides POSIX support on windows. ⚠ *NOTE:* Mintty tabs use a program called 'mintty' as the terminal emulator that is not based on the Windows Console API, rather it's rendered graphically by ConEmu. Mintty differs from the other tabs in that it supports xterm/xterm-256color TERM types, and does not work with ConEmu settings like color schemes and key bindings. As such, some differences in functionality are to be expected, such as Cmder not being able to apply a system-wide configuration to it. As a result mintty specific config is done via the `[%USERPROFILE%|$HOME]/.minttyrc` file. You may read more about Mintty and its config file [here](https://github.com/mintty/mintty). An example of setting Cmder portable terminal colors for mintty: From a bash/mintty shell: ``` cd $CMDER_ROOT/vendor git clone https://github.com/karlin/mintty-colors-solarized.git cd mintty-colors-solarized/ echo source \$CMDER_ROOT/vendor/mintty-colors-solarized/mintty-solarized-dark.sh>>$CMDER_ROOT/config/user_profile.sh ``` You may find some Monokai color schemes for mintty to match Cmder [here](https://github.com/oumu/mintty-color-schemes/blob/master/base16-monokai-mod.minttyrc). ### Changing Cmder Default `cmd.exe` Prompt Config File The default Cmder shell `cmd::Cmder` prompt is customized using `Clink` and is configured by editing a config file that exists in one of two locations: - Single User Portable Config `%CMDER_ROOT%\config\cmder_prompt_config.lua` - Shared Cmder install with Non-Portable Individual User Config `%CMDER_USER_CONFIG%\cmder_prompt_config.lua` If your Cmder setup does not have this file create it from `%CMDER_ROOT%\vendor\cmder_prompt_config.lua.default` Customizations include: - Colors. - Single/Multi-line. - Full path/Folder only. - `[user]@[host]` to the beginning of the prompt. - `~` for home directory. - `λ` symbol Documentation is in the file for each setting. ### Changing Cmder Default `cmd.exe` Shell Startup Behaviour Using Task Arguments 1. Press <kbd>Win</kbd> + <kbd>Alt</kbd> + <kbd>T</kbd> 1. Click either: * `1. {cmd::Cmder as Admin}` * `2. {cmd::Cmder}` 1. Add command line arguments where specified below: *Note: Pay attention to the quotes!* ``` cmd /s /k ""%ConEmuDir%\..\init.bat" [ADD ARGS HERE]" ``` ##### Command Line Arguments for `init.bat` | Argument | Description | Default | | ----------------------------- | ---------------------------------------------------------------------------------------------- | ------------------------------------- | | `/c [user cmder root]` | Enables user bin and config folders for 'Cmder as admin' sessions due to non-shared environment. | not set | | `/d` | Enables debug output. | not set | | `/f` | Enables Cmder Fast Init Mode. This disables some features, see pull request [#1492](https://github.com/cmderdev/cmder/pull/1942) for more details. | not set | | `/t` | Enables Cmder Timed Init Mode. This displays the time taken run init scripts | not set | | `/git_install_root [file path]` | User specified Git installation root path. | `%CMDER_ROOT%\vendor\Git-for-Windows` | | `/home [home folder]` | User specified folder path to set `%HOME%` environment variable. | `%userprofile%` | | `/max_depth [1-5]` | Define max recurse depth when adding to the path for `%cmder_root%\bin` and `%cmder_user_bin%` | 1 | | `/nix_tools [0-2]` | Define how `*nix` tools are added to the path. Prefer Windows Tools: 1, Prefer *nix Tools: 2, No `/usr/bin` in `%PATH%`: 0 | 1 | | `/svn_ssh [path to ssh.exe]` | Define `%SVN_SSH%` so we can use git svn with ssh svn repositories. | `%GIT_INSTALL_ROOT%\bin\ssh.exe` | | `/user_aliases [file path]` | File path pointing to user aliases. | `%CMDER_ROOT%\config\user_aliases.cmd` | | `/v` | Enables verbose output. | not set | | (custom arguments) | User defined arguments processed by `cexec`. Type `cexec /?` for more usage. | not set | ### Cmder Shell User Config Single user portable configuration is possible using the cmder specific shell config files. Edit the below files to add your own configuration: | Shell | Cmder Portable User Config | | ------------- | ----------------------------------------- | | Cmder | `%CMDER_ROOT%\config\user_profile.cmd` | | PowerShell | `$ENV:CMDER_ROOT\config\user_profile.ps1` | | Bash/Mintty | `$CMDER_ROOT/config/user_profile.sh` | Note: Bash and Mintty sessions will also source the `$HOME/.bashrc` file if it exists after it sources `$CMDER_ROOT/config/user_profile.sh`. You can write `*.cmd|*.bat`, `*.ps1`, and `*.sh` scripts and just drop them in the `%CMDER_ROOT%\config\profile.d` folder to add startup config to Cmder. | Shell | Cmder `Profile.d` Scripts | | ------------- | -------------------------------------------------- | | Cmder | `%CMDER_ROOT%\config\profile.d\*.bat and *.cmd` | | PowerShell | `$ENV:CMDER_ROOT\config\profile.d\*.ps1` | | Bash/Mintty | `$CMDER_ROOT/config/profile.d/*.sh` | #### Git Status Opt-Out To disable Cmder prompt git status globally add the following to `~/.gitconfig` or locally for a single repo `[repo]/.git/config` and start a new session. *Note: This configuration is not portable* ``` [cmder] status = false # Opt out of Git status for 'ALL' Cmder supported shells. cmdstatus = false # Opt out of Git status for 'Cmd.exe' shells. psstatus = false # Opt out of Git status for 'Powershell.exe and 'Pwsh.exe' shells. shstatus = false # Opt out of Git status for 'bash.exe' shells. ``` ### Aliases #### Cmder(`Cmd.exe`) Aliases You can define simple aliases for `cmd.exe` sessions with a command like `alias name=command`. Cmd.exe aliases support optional parameters through the `$1-9` or the `$*` special characters so the alias `vi=vim.exe $*` typed as `vi [filename]` will open `[filename]` in `vim.exe`. Cmd.exe aliases can also be more complex. See: [DOSKEY.EXE documentation](https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/doskey) for additional details on complex aliases/macros for `cmd.exe` Aliases defined using the `alias.bat` command will automatically be saved in the `%CMDER_ROOT%\config\user_aliases.cmd` file To make an alias and/or any other profile settings permanent add it to one of the following: Note: These are loaded in this order by `$CMDER_ROOT/vendor/init.bat`. Anything stored in `%CMDER_ROOT%` will be a portable setting and will follow cmder to another machine. * `%CMDER_ROOT%\config\profile.d\*.cmd` and `\*.bat` * `%CMDER_ROOT%\config\user_aliases.cmd` * `%CMDER_ROOT%\config\user_profile.cmd` #### Bash.exe|Mintty.exe Aliases Bash shells support simple and complex aliases with optional parameters natively so they work a little different. Typing `alias name=command` will create an alias only for the current running session. To make an alias and/or any other profile settings permanent add it to one of the following: Note: These are loaded in this order by `$CMDER_ROOT/vendor/git-for-windows/etc/profile.d/cmder.sh`. Anything stored in `$CMDER_ROOT` will be a portable setting and will follow cmder to another machine. * `$CMDER_ROOT/config/profile.d/*.sh` * `$CMDER_ROOT/config/user_profile.sh` * `$HOME/.bashrc` If you add bash aliases to `$CMDER_ROOT/config/user_profile.sh` they will be portable and follow your Cmder folder if you copy it to another machine. `$HOME/.bashrc` defined aliases are not portable. #### PowerShell.exe Aliases PowerShell has native simple alias support, for example `[new-alias | set-alias] alias command`, so complex aliases with optional parameters are not supported in PowerShell sessions. Type `get-help [new-alias|set-alias] -full` for help on PowerShell aliases. To make an alias and/or any other profile settings permanent add it to one of the following: Note: These are loaded in this order by `$ENV:CMDER_ROOT\vendor\user_profile.ps1`. Anything stored in `$ENV:CMDER_ROOT` will be a portable setting and will follow cmder to another machine. * `$ENV:CMDER_ROOT\config\profile.d\*.ps1` * `$ENV:CMDER_ROOT\config\user_profile.ps1` ### SSH Agent To start the vendored SSH agent simply call `start-ssh-agent`, which is in the `vendor/git-for-windows/cmd` folder. If you want to run SSH agent on startup, include the line `@call "%GIT_INSTALL_ROOT%/cmd/start-ssh-agent.cmd"` in `%CMDER_ROOT%/config/user_profile.cmd` (usually just uncomment it). ### Vendored Git Cmder is by default shipped with a vendored Git installation. On each instance of launching Cmder, an attempt is made to locate any other user provided Git binaries. Upon finding a `git.exe` binary, Cmder further compares its version against the vendored one _by executing_ it. The vendored `git.exe` binary is _only_ used when it is more recent than the user-installed one. You may use your favorite version of Git by including its path in the `%PATH%` environment variable. Moreover, the **Mini** edition of Cmder (found on the [downloads page](https://github.com/cmderdev/cmder/releases)) excludes any vendored Git binaries. ### Using external Cygwin/Babun, MSys2, WSL, or Git for Windows SDK with Cmder. You may run bash (the default shell used on Linux, macOS and GNU/Hurd) externally on Cmder, using the following instructions: 1. Setup a new task by pressing <kbd>Win</kbd> +<kbd>Alt</kbd> + <kbd>T</kbd>. 1. Click the `+` button to add a task. 1. Name the new task in the top text box. 1. Provide task parameters, this is optional. 1. Add `cmd /c "[path_to_external_env]\bin\bash --login -i" -new_console` to the `Commands` text box. **Recommended Optional Steps:** Copy the `vendor/cmder_exinit` file to the Cygwin/Babun, MSys2, or Git for Windows SDK environments `/etc/profile.d/` folder to use portable settings in the `$CMDER_ROOT/config` folder. Note: MinGW could work if the init scripts include `profile.d` but this has not been tested. The destination file extension depends on the shell you use in that environment. For example: * bash - Copy to `/etc/profile.d/cmder_exinit.sh` * zsh - Copy to `/etc/profile.d/cmder_exinit.zsh` Uncomment and edit the below line in the script to use Cmder config even when launched from outside Cmder. ``` # CMDER_ROOT=${USERPROFILE}/cmder # This is not required if launched from Cmder. ``` ### Customizing user sessions using `init.bat` custom arguments. You can pass custom arguments to `init.bat` and use `cexec.cmd` in your `user_profile.cmd` to evaluate these arguments then execute commands based on a particular flag being detected or not. `init.bat` creates two shortcuts for using `cexec.cmd` in your profile scripts. #### `%ccall%` - Evaluates flags, runs commands if found, and returns to the calling script and continues. ``` ccall=call C:\Users\user\cmderdev\vendor\bin\cexec.cmd ``` Example: `%ccall% /startnotepad start notepad.exe` #### `%cexec%` - Evaluates flags, runs commands if found, and does not return to the calling script. ``` cexec=C:\Users\user\cmderdev\vendor\bin\cexec.cmd ``` Example: `%cexec% /startnotepad start notepad.exe` It is useful when you have multiple tasks to execute `cmder` and need it to initialize the session differently depending on the task chosen. To conditionally start `notepad.exe` when you start a specific `cmder` task: * Press <kbd>win</kbd>+<kbd>alt</kbd>+<kbd>t</kbd> * Click `+` to add a new task. * Add the below to the `Commands` block: ```batch cmd.exe /k ""%ConEmuDir%\..\init.bat" /startnotepad" ``` * Add the below to your `%cmder_root%\config\user_profile.cmd` ```batch %ccall% "/startNotepad" "start" "notepad.exe"` ``` To see detailed usage of `cexec`, type `cexec /?` in cmder. ### Integrating Cmder with [Hyper](https://github.com/zeit/hyper), [Microsoft VS Code](https://code.visualstudio.com/), and your favorite IDEs Cmder by default comes with a vendored ConEmu installation as the underlying terminal emulator, as stated [here](https://conemu.github.io/en/cmder.html). However, Cmder can in fact run in a variety of other terminal emulators, and even integrated IDEs. Assuming you have the latest version of Cmder, follow the following instructions to get Cmder working with your own terminal emulator. For instructions on how to integrate Cmder with your IDE, please read our [Wiki section](https://github.com/cmderdev/cmder/wiki#cmder-integration). ## Upgrading The process of upgrading Cmder depends on the version/build you are currently running. If you have a `[cmder_root]/config/user[-|_]conemu.xml`, you are running a newer version of Cmder, follow the below process: 1. Exit all Cmder sessions and relaunch `[cmder_root]/cmder.exe`, this backs up your existing `[cmder_root]/vendor/conemu-maximus5/conemu.xml` to `[cmder_root]/config/user[-|_]conemu.xml`. * The `[cmder_root]/config/user[-|_]conemu.xml` contains any custom settings you have made using the 'Setup Tasks' settings dialog. 2. Exit all Cmder sessions and backup any files you have manually edited under `[cmder_root]/vendor`. * Editing files under `[cmder_root]/vendor` is not recommended since you will need to re-apply these changes after any upgrade. All user customizations should go in `[cmder_root]/config` folder. 3. Delete the `[cmder_root]/vendor` folder. 4. Extract the new `cmder.zip` or `cmder_mini.zip` into `[cmder_root]/` overwriting all files when prompted. If you do not have a `[cmder_root]/config/user[-|_]conemu.xml`, you are running an older version of cmder, follow the below process: 1. Exit all Cmder sessions and backup `[cmder_root]/vendor/conemu-maximus5/conemu.xml` to `[cmder_root]/config/user[-|_]conemu.xml`. 2. Backup any files you have manually edited under `[cmder_root]/vendor`. * Editing files under `[cmder_root]/vendor` is not recommended since you will need to re-apply these changes after any upgrade. All user customizations should go in `[cmder_root]/config` folder. 3. Delete the `[cmder_root]/vendor` folder. 4. Extract the new `cmder.zip` or `cmder_mini.zip` into `[cmder_root]/` overwriting all files when prompted. ## Current development builds You can download builds of the current development branch by going to AppVeyor via the following link: [](https://ci.appveyor.com/project/MartiUK/cmder/branch/master/artifacts) ## License All software included is bundled with own license The MIT License (MIT) Copyright (c) 2016 Samuel Vasko Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
nmn / Lexical Binding Getter Setter ProposalA proposal for extending JS syntax to support lexically scoped getters and setters for variable bindings
Kolos65 / AsyncBindingBinding async sequences to state variables in SwiftUI.
kenmaz / StrongSelfRewriterReplace variable name of `guard let self = self` optional binding using SwiftSyntax
oliversheridanmethven / PyarvPython bindings of approximate random variables
AbsaOSS / Env BinderBinding environment variables to GO structures
