To my knowledge, the three most popular ways how to parse command line arguments in C are: Getopt (#include <unistd.h> from the POSIX C Library), which can solve simple argument parsing tasks. If you’re a bit familiar with bash, the getopt built-in of bash is based on Getopt from the GNU libc. Argp (#include <argp.h> … Read more
Update 01/17/17: Updated the example for Swift 3. Process has been renamed to CommandLine. Update 09/30/2015: Updated the example to work in Swift 2. It’s actually possible to do this without Foundation or C_ARGV and C_ARGC. The Swift standard library contains a struct CommandLine which has a collection of Strings called arguments. So you could … Read more
The man pages is the best source of information you can find… and is at your fingertips: man mkdir yields this about -p switch: -p, –parents no error if existing, make parent directories as needed Use case example: Assume I want to create directories hello/goodbye but none exist: $mkdir hello/goodbye mkdir:cannot create directory ‘hello/goodbye’: No … Read more
Once gdb starts, you can run the program using “r args“. So if you are running your code by: $ executablefile arg1 arg2 arg3 Debug it on gdb by: $ gdb executablefile (gdb) r arg1 arg2 arg3
The store_true option automatically creates a default value of False. Likewise, store_false will default to True when the command-line argument is not present. The source for this behavior is succinct and clear: http://hg.python.org/cpython/file/2.7/Lib/argparse.py#l861 The argparse docs aren’t clear on the subject, so I’ll update them now: http://hg.python.org/cpython/rev/49677cc6d83a
You can use eval to execute a string: eval $illcommando
The suggestions for boost::program_options and GNU getopt are good ones. However, for simple command line options I tend to use std::find For example, to read the name of a file after a -f command line argument. You can also just detect if a single-word option has been passed in like -h for help. #include <algorithm> … Read more
If your shell is bash (amongst others), a shortcut for $(cat afile) is $(< afile), so you’d write: mycommand “$(< file.txt)” Documented in the bash man page in the ‘Command Substitution’ section. Alterately, have your command read from stdin, so: mycommand < file.txt
with this script in file.sh #!/bin/bash echo Your container args are: “$@” and this Dockerfile FROM ubuntu:14.04 COPY ./file.sh / ENTRYPOINT [“/file.sh”] you should be able to: % docker build -t test . % docker run test hello world Your container args are: hello world
For most cases you do not need an external parser. Scala’s pattern matching allows consuming args in a functional style. For example: object MmlAlnApp { val usage = “”” Usage: mmlaln [–min-size num] [–max-size num] filename “”” def main(args: Array[String]) { if (args.length == 0) println(usage) val arglist = args.toList type OptionMap = Map[Symbol, Any] … Read more