GNU Emacs Manual: Regexps This manual describes regular expression features that users typically use. See Regular Expressions in The Emacs Lisp Reference Manual, for additional features used mainly in Lisp programs. Regular expressions have a syntax in which a few characters are special constructs and the rest are ordinary. An ordinary character matches that same character and nothing else. For example, ‘f’ is not a special character, so it is ordinary, and therefore ‘f’ is a regular expression that matches the string ‘f’ and no other string. Any two regular expressions and can be concatenated. . is a special character that matches any single character except a newline. is not a construct by itself; it is a postfix operator that means to match the preceding regular expression repetitively any number of times, as many times as possible. ‘*’ always applies to the smallest possible preceding expression. The matcher processes a ‘*’ construct by matching, immediately, as many repetitions as can be found. .
developer.mozilla Regular expressions are used with the RegExp methods test() and exec() and with the String methods match(), replace(), search(), and split(). When you want to know whether a pattern is found in a string, use the test() or search() methods; for more information (but slower execution) use the exec() or match() methods. If you use exec() or match() and if the match succeeds, these methods return an array and update properties of the associated regular expression object and also of the predefined regular expression object, RegExp. If the match fails, the exec() method returns null (which coerces to false). In the following example, the script uses the exec() method to find a match in a string. const myRe = /d(b+)d/g;const myArray = myRe.exec("cdbbdbsbz"); If you do not need to access the properties of the regular expression, an alternative way of creating myArray is with this script: const myArray = /d(b+)d/g.exec("cdbbdbsbz"); However, if you have this script:
Time In an operating system, the time (clock) is determined by four parts: time value, time standard, time zone, and Daylight Saving Time (DST) if applicable. This article explains what they are and how to read/set them. Hardware clock and system clock A computer has two clocks that need to be considered: the "Hardware clock" and the "System/software clock". Hardware clock (a.k.a. the Real Time Clock (RTC) or CMOS clock) stores the values of: Year, Month, Day, Hour, Minute, and the Seconds. System clock (a.k.a. the software clock) keeps track of: time, time zone, and DST if applicable. Read clock To check the current system clock time (presented both in local time and UTC): $ timedatectl Run the same command as root to display also the hardware clock time. Set clock To set the local time of the system clock directly: # timedatectl set-time "yyyy-MM-dd hh:mm:ss" For example: # timedatectl set-time "2014-05-26 11:13:54" sets the time to May 26th, year 2014, 11:13 and 54 seconds. RTC clock Time standard
tshark - The Wireshark Network Analyzer 1.12.2 TShark is a network protocol analyzer. It lets you capture packet data from a live network, or read packets from a previously saved capture file, either printing a decoded form of those packets to the standard output or writing the packets to a file. TShark's native capture file format is pcapng format, which is also the format used by Wireshark and various other tools. Without any options set, TShark will work much like tcpdump. It will use the pcap library to capture traffic from the first available network interface and displays a summary line on the standard output for each received packet. When run with the -r option, specifying a capture file from which to read, TShark will again work much like tcpdump, reading packets from the file and displaying a summary line on the standard output for each packet read. Compressed file support uses (and therefore requires) the zlib library. Packet capturing is performed with the pcap library.