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How to detect if my shell script is running through a pipe?
...eas
(if [ -t 1 ] ; then echo terminal; else echo "not a terminal"; fi) | cat
returns "not a terminal", because the output of the parenthetic is piped to cat.
The -t flag is described in man pages as
-t fd True if file descriptor fd is open and refers to a terminal.
... where fd can be ...
How to insert a text at the beginning of a file?
...ile
Or you can use Command Grouping:
$ { echo -n '<added text> '; cat file; } >file.new
$ mv file{.new,}
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Linux command (like cat) to read a specified quantity of characters
Is there a command like cat in linux which can return a specified quantity of characters from a file?
9 Answers
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Function to clear the console in R and RStudio
...
cat("\014")
is the code to send CTRL+L to the console, and therefore will clear the screen.
Far better than just sending a whole lot of returns.
...
dynamic_cast and static_cast in C++
...rwise, you'll get a NULL pointer.
But B2D casts are a little more complicated. Consider the following code:
#include <iostream>
using namespace std;
class Base
{
public:
virtual void DoIt() = 0; // pure virtual
virtual ~Base() {};
};
class Foo : public Base
{
public:
virt...
How can I find all matches to a regular expression in Python?
...or over MatchObject objects.
Example:
re.findall( r'all (.*?) are', 'all cats are smarter than dogs, all dogs are dumber than cats')
# Output: ['cats', 'dogs']
[x.group() for x in re.finditer( r'all (.*?) are', 'all cats are smarter than dogs, all dogs are dumber than cats')]
# Output: ['all cats...
How to get the part of a file after the first line that matches a regular expression?
...vior of sed of printing each line after executing its script on it, -e indicated a script to sed, /TERMINATE/,$ is an address (line) range selection meaning the first line matching the TERMINATE regular expression (like grep) to the end of the file ($), and p is the print command which prints the cu...
How do I view 'git diff' output with my preferred diff tool/ viewer?
...e new-file new-hex new-mode
"<path_to_diff_executable>" "$2" "$5" | cat
--8<-(snap)--
As you can see, only the second ("old-file") and fifth ("new-file") arguments will be
passed to the diff tool.
2) Type
$ git config --global diff.external <path_to_wrapper_script>
at the comma...
How big can a user agent string get?
...ind the fastest hash algorithm that didn't produce any collisions. For my PHP environment I found md5 performed quickly at 2.3 seconds with no collisions. Interestingly I tried crc32 and crc32b and they also performed at 2.3 seconds with no collisions. But, because md5 has more combinations than c...
How to pattern match using regular expression in Scala?
... @MichaelLafayette: Inside of a character class ([]), the caret indicates negation, so [^\s] means 'non-whitespace'.
– Fabian Steeg
Jun 6 '16 at 12:02
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