How to get the one character’s next character in ASCII table in Bash? For example, if I have ‘a’ in variable i, how to get ‘b’? First, we need to get the integer value for the character. char=’b’ charint=$(printf “%d” “‘$char'”) Then, we increase the integer by one let charint=$charint+1 Last, we can get the…
How to delete or get the number in the tail from a string in shell script (bash script)? Okay to call other tools. For example, from “/dev/sda8”, I want to get “/dev/sda” and “8” separately. This can be achieved by using sed as follows. To get the string after deleting the tailing numbers, we can…
How to split a string by string in PHP? For example, “a string separated by space” => [“a”, “string”, “separated”, “by”, “space”] and “a,string,separated,by,comma” => [“a”, “string”, “separated”, “by”, “comma”] The commonly used `explode()` is not enough here because multiple delimiters should be consider as one (such as ” “, 3 spaces together, is consider…
How to split a string by string in Bash? For example, “a string separated by space” => [“a”, “string”, “separated”, “by”, “space”] and “a,string,separated,by,comma” => [“a”, “string”, “separated”, “by”, “comma”] You can convert a string to an array using the grammar like inarr=(${a}) If the delimiter is not space and delimiter is a single character…
Could you list the most important features or aspects for the C++ programming languages that describe its most important features/domains that are different from the others? For C++, as in Going Native 2012 Keynote by Bjarne Stroustrup: light-weight abstraction Key strengths: infrastructure software resource-constrained applications
In C++, what’s the standard or common data structure for a list of objects? In C++, the common data structure for a sequence (“list”) of objects may be std::vector. A vector is a dynamically resizable array. It is “The most extensively used container in the C++ Standard Library …, offering a combination of dynamic memory…
In C, what’s the standard or common data structure for a list of objects? In C, one common way to store a list/collection of objects of the same type is to use one-dimensional arrays. In C, an array is a collection of data objects of the same type. An array is in a contiguous memory…
In C, how to get the hostname of the node? In C, you may use the gethostname function. #include <unistd.h> int gethostname(char *name, size_t namelen); The gethostname() function shall return the standard host name for the current machine. The namelen argument shall specify the size of the array pointed to by the name argument. The…
In C++, how to get the hostname of the node? In C++, the C way works too. However, with Boost, you can use the boost::asio::ip::host_name() function to get the hostname as a std::string: namespace boost { namespace asio { namespace ip { /// Get the current host name. BOOST_ASIO_DECL std::string host_name(); … More at http://www.boost.org/doc/libs/1_63_0/boost/asio/ip/host_name.hpp…
In Go lang, how to get the hostname of the node? In Go, you can use the os.Hostname() function to get the hostname of the node. func Hostname() (name string, err error) Hostname returns the host name reported by the kernel. One example is as follows. The main.go source code: package main import ( “fmt”…
Getting the hostname of the node running a program can be useful in various scenarios, such as creating logs with the hostname, identifying which node a script is running on, or configuring a distributed system with different nodes. In Bash, there are several ways to retrieve the hostname of the machine, as mentioned in the…
In Bash, how to convert an epoch timestamp to a human readable date format? In Bash, you can use the date command’s -d option: date -d @<your epoch> Here @ specifies the epoch timestamp. One example: $ date -d @1490157520.05 Wed Mar 22 12:38:40 HKT 2017
In Python, how to get the hostname of the node? In Python, you can get the hostname by the socket.gethostname() library function in the socket module: import socket hostname = socket.gethostname() Example: $ python Python 2.7.5 (default, Nov 6 2016, 00:28:07) [GCC 4.8.5 20150623 (Red Hat 4.8.5-11)] on linux2 Type “help”, “copyright”, “credits” or “license”…
In C, how to get the epoch timestamp, the number of seconds passed since the epoch? In C, from man 7 time: UNIX systems represent time in seconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC). A program can determine the calendar time using gettimeofday(2), which returns time (in seconds and microseconds) that have elapsed since…
How to convert an epoch timestamp to a human readable date format? In Python: import time time.strftime(“%a, %d %b %Y %H:%M:%S %Z”, time.localtime(epoch)) One example: $ python Python 2.7.5 (default, Nov 6 2016, 00:28:07) [GCC 4.8.5 20150623 (Red Hat 4.8.5-11)] on linux2 Type “help”, “copyright”, “credits” or “license” for more information. >>> import time >>>…
In Java, how to get the epoch timestamp, the number of seconds passed since the epoch? In Java, you can get the current time in milliseconds and then calculate the epoch time: long ts = System.currentTimeMillis()/1000; Example: $ wget –quiet https://github.com/albertlatacz/java-repl/releases/download/428/javarepl-428.jar -O /tmp/javarepo-428.jar && java -jar /tmp/javarepo-428.jar Welcome to JavaREPL version 428 (Java HotSpot(TM) 64-Bit…
In Go lang, how to get the epoch timestamp, the number of seconds passed since the epoch? In Go, you can use the time.Now() func to get current time and its Unix() func to convert it into an epoch timestamp: import(“time”) func getEpochTime() int64 { return time.Now().Unix() } If you would convert a time string…
In PHP, how to get the epoch timestamp, the number of seconds passed since the epoch? In PHP, you can use the time() function. ts = time(); To get the microsecond together too as a float number, use the microtime(true) function. ts2 = microtime(true); Example: $ php -a Interactive shell php > echo time() ….
In Perl, how to get the epoch timestamp, the number of seconds passed since the epoch? In Perl, to get the epoch time, call the time function: my $ts = time Example: $ perl -e ‘print time . “n”‘ 1491473202
In Python, how to get the epoch time (the number of seconds since epoch)? In Python, you can get the epoch time by calling time.time() which return a floating number: import time print time.time() If you would like to get only the number of seconds, you may convert it to an integer. One example is…