As other people explained, the problem is that the I/O redirection is done before the sort command is executed, so the file is truncated before sort gets a chance to read it. If you think for a bit, the reason why is obvious – the shell handles the I/O redirection, and must do that before … Read more
In the pipeline, two new processes are created: one for a shell to execute the echo command, and one for a shell to execute the read command. Since both subshells exit after they complete, the x variable is not available after the pipeline completes. (In bash 4, the lastpipe option was introduced to allow the … Read more
You can use IPC::Open3 to achieve bi-directional communication with child. use strict; use IPC::Open3; my $pid = open3(\*CHLD_IN, \*CHLD_OUT, \*CHLD_ERR, ‘cat’) or die “open3() failed $!”; my $r; for(my $i=1;$i<10;$i++) { print CHLD_IN “$i\n”; $r = <CHLD_OUT>; print “Got $r from child\n”; }
I just found out a simpler answer to part of my question. To quickly and synchronously detect if piped content is being passed to the current script in Node.js, use the process.stdin.isTTY boolean: $ node -p -e ‘process.stdin.isTTY’ true $ echo ‘foo’ | node -p -e ‘process.stdin.isTTY’ undefined So, in a script, you could do … Read more
You might also run into a problem with grep buffering when inside a pipe. ie, you don’t see the output from tail –follow=name file.txt | grep something > output.txt since grep will buffer its own output. Use the –line-buffered switch for grep to work around this: tail –follow=name file.txt | grep –line-buffered something > output.txt … Read more
For multi line version you can do this after selecting the text: :'<,’>:w !command<CR> See the official Vim docs at :help :w_c. You can map it to simple Visual mode shortcut like this: xnoremap <leader>c <esc>:'<,’>:w !command<CR> Hit <leader key>+c in visual mode to send the selected text to a stdin of the command. stdout … Read more
In Angular a good technique for sharing common directives, components, pipes, etc. is to use a so called shared module. Those modules declare and export common parts, to make them usable for any of your other modules. The fundamentals section of the angular documentation is a very good read about shared modules. Let’s take as … Read more
The parameter has this syntax: {minIntegerDigits}.{minFractionDigits}-{maxFractionDigits} So your example of ‘1.2-2’ means: A minimum of 1 digit will be shown before decimal point It will show at least 2 digits after decimal point But not more than 2 digits
Piping to another process (although this won’t accomplish what you said you are trying to do): command1 | command2 This will send the output of command1 as the input of command2. -exec on a find (this will do what you want to do, but it’s specific to find): find . -name ‘*.foo’ -exec cat {} … Read more
I don’t have a ksh, but I’ve managed to do it with bash. /home/galymzhan/.bash_profile: export VAR_FROM_PROFILE=”foobar” /home/galymzhan/test.php: #!/usr/bin/php -n <?php if (!isset($_SERVER[‘VAR_FROM_PROFILE’])) { $descriptors = array(0 => array(‘pipe’, ‘r’), 1 => array(‘pipe’, ‘w’)); $process = proc_open(‘bash’, $descriptors, $pipes); fwrite($pipes[0], escapeshellcmd(‘source /home/galymzhan/.bash_profile’) . “\n”); fwrite($pipes[0], escapeshellcmd(‘/home/galymzhan/test.php’) . “\n”); fclose($pipes[0]); echo “Output:\n”; echo stream_get_contents($pipes[1]); echo “\n”; fclose($pipes[1]); … Read more