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An example of how to use getopts in bash
...of missing value.
OPTARG - is set to current argument value,
OPTERR - indicates if Bash should display error messages.
So the code can be:
#!/usr/bin/env bash
usage() { echo "$0 usage:" && grep " .)\ #" $0; exit 0; }
[ $# -eq 0 ] && usage
while getopts ":hs:p:" arg; do
case $ar...
unix diff side-to-side results?
...put in two columns
Hence, say:
diff -y /tmp/test1 /tmp/test2
Test
$ cat a $ cat b
hello hello
my name my name
is me is you
Let's compare them:
$ diff -y a b
hello hello...
Why does the order in which libraries are linked sometimes cause errors in GCC?
...o see real command lines).
Common files shared by all below commands
$ cat a.cpp
extern int a;
int main() {
return a;
}
$ cat b.cpp
extern int b;
int a = b;
$ cat d.cpp
int b;
Linking to static libraries
$ g++ -c b.cpp -o b.o
$ ar cr libb.a b.o
$ g++ -c d.cpp -o d.o
$ ar cr libd.a d.o
$ ...
What is cURL in PHP?
...mmandline:
el@apollo:/home/el$ curl http://i.imgur.com/4rBHtSm.gif > mycat.gif
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 492k 100 492k 0 0 1077k 0 --:--:-- --:-...
Why do people write the #!/usr/bin/env python shebang on the first line of a Python script?
...xible.
In Unix, an executable file that's meant to be interpreted can indicate what interpreter to use by having a #! at the start of the first line, followed by the interpreter (and any flags it may need).
If you're talking about other platforms, of course, this rule does not apply (but that "she...
Initializing multiple variables to the same value in Java
...
Are these the same object? If I later do one = "cat" will two.equals("cat") return true?
– Aequitas
Sep 24 '15 at 5:48
...
Rails: FATAL - Peer authentication failed for user (PG::Error)
...s app with postgres YAML and 'pg' gem in the Gemfile:
$ rails new my_application -d postgresql
2) Give it some CRUD functionality. If you're just seeing if postgres works, create a scaffold:
$ rails g scaffold cats name:string age:integer colour:string
3) As of rails 4.0.1 the -d postgresql op...
What's the best way to send a signal to all members of a process group?
...
kill -74313 -bash: kill: 74313: invalid signal specification If i add the kill -15 -GPID it worked perfectly.
– Adam Peck
Dec 24 '08 at 20:17
52
...
Automatic counter in Ruby for each?
...ample, if you want to map with an index or something like that) you can concatenate enumerators with the each_with_index method, or simply use with_index:
blahs.each_with_index.map { |blah, index| something(blah, index)}
blahs.map.with_index { |blah, index| something(blah, index) }
This is somet...
Why is parenthesis in print voluntary in Python 2.7?
...effect when it comes to UTF-8.
>> greek = dict( dog="σκύλος", cat="γάτα" )
>> print greek['dog'], greek['cat']
σκύλος γάτα
>> print (greek['dog'], greek['cat'])
('\xcf\x83\xce\xba\xcf\x8d\xce\xbb\xce\xbf\xcf\x82', '\xce\xb3\xce\xac\xcf\x84\xce\xb1')
The last ...