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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
...
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...
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.
...
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 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 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 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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