backticks

问题 I\'m trying to understand what backticks do in R. From what I can tell, this is not explained in the ?Quotes documentation page for R. For example, at the R console: \"[[\" # [1] \"[[\" `[[` # .Primitive(\"[[\") It seem to be returning the equivalent to: get(\"[[\") 回答1: A pair of backticks is a way to refer to names or combinations of symbols that are otherwise reserved or illegal. Reserved are words like if are part of the language, while illegal includes non-syntactic combinations like c a

问题 What is the equivalent of the backticks found in Ruby and Perl in Python? That is, in Ruby I can do this: foo = `cat /tmp/baz` What does the equivalent statement look like in Python? I\'ve tried os.system(\"cat /tmp/baz\") but that puts the result to standard out and returns to me the error code of that operation. 回答1: output = os.popen('cat /tmp/baz').read() 回答2: The most flexible way is to use the subprocess module: import subprocess out = subprocess.run(["cat", "/tmp/baz"], capture_output

问题 There are two ways to capture the output of command line in bash : Legacy Bourne shell backticks `` : var=`command` $() syntax (which as far as I know is Bash specific, or at least not supported by non-POSIX old shells like original Bourne) var=$(command) Is there any benefit to using the second syntax compared to backticks? Or are the two fully 100% equivalent? 回答1: The major one is the ability to nest them, commands within commands, without losing your sanity trying to figure out if some

问题 When working with Bash, I can put the output of one command into another command like so: my_command `echo Test` would be the same thing as my_command Test (Obviously, this is just a non-practical example.) I\'m just wondering if you can do the same thing in Batch. 回答1: You can do it by redirecting the output to a file first. For example: echo zz > bla.txt set /p VV=<bla.txt echo %VV% 回答2: You can get a similar functionality using cmd.exe scripts with the for /f command: for /f "usebackq

问题 In JavaScript, a backtick † seems to work the same as a single quote. For instance, I can use a backtick to define a string like this: var s = `abc`; Is there any way in which the behavior of the backtick actually differs from that of a single quote? † Note that among programmers, \"backtick\" is one name for what is more generally called the grave accent. Programmers also sometimes use the alternate names \"backquote\" and \"backgrave\". Also, on Stack Overflow and elsewhere, other common