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Meaning of $? (dollar question mark) in shell scripts
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$? returns the exit value of the last executed command. echo $? prints that value on console. zero implies a successful execution while non-zero values are mapped to various reason for failure.
Hence when scripting; I tend to use the following syntax
if [ $? -eq 0 ]; then
# do something...
Conditional import of modules in Python
... user; here's pySerial doing it as an example.
serial/__init__.py
import sys
if sys.platform == 'cli':
from serial.serialcli import Serial
else:
import os
# chose an implementation, depending on os
if os.name == 'nt': # sys.platform == 'win32':
from serial.serialwin32 imp...
How to quit scala 2.11.0 REPL?
..., just use colon q.
:q
Additionally, exit was deprecated in 2.10.x with sys.exit suggested instead, so this works as well:
sys.exit
As a side note, I think they did this so you can distinguish between exiting the scala console in sbt and exiting sbt itself, though I could be wrong.
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Converting a generic list to a CSV string
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You can use String.Join.
String.Join(
",",
Array.ConvertAll(
list.ToArray(),
element => element.ToString()
)
);
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How to access environment variable values?
...:\Python. If you want to find out while running python you can do:
import sys
print(sys.prefix)
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What do the terms “CPU bound” and “I/O bound” mean?
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It's pretty intuitive:
A program is CPU bound if it would go faster if the CPU were faster, i.e. it spends the majority of its time simply using the CPU (doing calculations). A program that computes new digits of π will typically be CP...
TLSF源码及算法介绍 - 开源 & Github - 清泛网 - 专注C/C++及内核技术
... USE_SBRK (0) */
/*#define USE_MMAP (0) */
#ifndef USE_PRINTF
#define USE_PRINTF (1)
#endif
#include <string.h>
#ifndef TLSF_USE_LOCKS
#define TLSF_USE_LOCKS (0)
#endif
#ifndef TLSF_STATISTIC
#define TLSF_STATISTIC (0)
#endif
#ifndef USE_MMAP
#define USE_M...
Convert a matrix to a 1 dimensional array
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It might be so late, anyway here is my way in converting Matrix to vector:
library(gdata)
vector_data<- unmatrix(yourdata,byrow=T))
hope that will help
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How do I turn off Oracle password expiration?
...rd;
Below is a little SQL*Plus script that a privileged user (e.g. user 'SYS') can use to reset a user's password to the current existing hashed value stored in the database.
EDIT: Older versions of Oracle store the password or password-hash in the pword column, newer versions of Oracle store the...
How to convert an NSString into an NSNumber
How can I convert a NSString containing a number of any primitive data type (e.g. int , float , char , unsigned int , etc.)? The problem is, I don't know which number type the string will contain at runtime.
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