$(echo foo bar) is indeed a command substitution. In this specific example, you don’t need double quotes because a variable assignment creates a “double quote context” for its right-hand side, so VAR=$(…) is equivalent to VAR=”$(…)”. In bash, you don’t need double quotes in export VAR=$(…) or declare VAR=$(…). But you do need the double … Read more
Sorry, that’s not the way constants in PHP work. You can put variables in double quotes and heredocs but not constants.
The warnings about foregoing enclosures are valid, but you’ve said they don’t apply to your use-case. I’m wondering why you can’t just use something like this? <?php $fields = array( “field 1″,”field 2″,”field3hasNoSpaces” ); fputs(STDOUT, implode(‘,’, $fields).”\n”);
Use $(commands) instead: $ echo “hello1-$(echo hello2-$(echo hello3-$(echo hello4)))” hello1-hello2-hello3-hello4 $(commands) does the same thing as backticks, but you can nest them. You may also be interested in Bash range expansions: echo hello{1..10} hello1 hello2 hello3 hello4 hello5 hello6 hello7 hello8 hello9 hello10
Use ssh deploy@hera ‘kill -9 `ps -ef | grep MapReduceNode | grep -v “grep” | awk -F ” ” ‘”‘”‘{print $2}'”‘”‘ | head -n 1`’ Explanation: ssh deploy@hera ‘kill -9 `ps -ef | grep MapReduceNode | grep -v “grep” | awk -F ” ” ‘”‘”‘{print $2}'”‘”‘ | head -n 1`’ > 1 <>2<> 3 <>4<> … Read more
The reason your current attempt doesn’t work is that single-quoted (‘) string literals in PowerShell are verbatim strings – no attempt will be made at expanding subexpression pipelines or variable expressions. If you want an expandable string literal without having to escape all the double-quotes (“) contained in the string itself, use a here-string: $mynumber … Read more
js2010’s helpful answer is correct in that the use of Start-Process is incidental to your question and that the behavior is specific to PowerShell’s CLI (powershell.exe for Windows PowerShell, and pwsh for PowerShell (Core) 6+): On Windows[1], there are two layers of evaluation to consider: (a) The initial parsing of the command line into arguments. … Read more
TL;DR A single argument must be shorter than MAX_ARG_STRLEN. Analysis According to this link: And as additional limit since 2.6.23, one argument must not be longer than MAX_ARG_STRLEN (131072). This might become relevant if you generate a long call like “sh -c ‘generated with long arguments’”. This is exactly the “problem” identified by the OP. … Read more
PowerShell CLI fundamentals: PowerShell editions: The CLI of the legacy, bundled-with-Windows Windows PowerShell edition is powershell.exe, whereas that of the cross-platform, install-on-demand PowerShell (Core) 7+ edition is pwsh.exe (just pwsh on Unix-like platforms). Interactive use: By default, unless code to execute is specified (via -Command (-c) or -File (-f, see below), an interactive session is … Read more
A quoted heredoc allows you to omit the outer quotes: ssh user@host <<‘END’ df | grep /dev/ | awk ‘BEGIN{print “DISK”, “%USAGE”, “STATUS”} {split($5, a, “%”); var=”GREEN”; print $1, $5, var}’ | column -t END