Tip of the hat to @gniourf_gniourf and @chepner for their help. tl;dr To be safe, double-quote: it’ll work in all cases, across all POSIX-like shells. If you want to add a ~-based path, selectively leave the ~/ unquoted to ensure that ~ is expanded; e.g.: export PATH=~/”bin:$PATH”. See below for the rules of ~ expansion …
You need to capture both the std out and std err in the process. You can then write std out to a file/mail or similar. See this article for more info, and in particular note the StreamGobbler mechanism that captures stdout/err in separate threads. This is essential to prevent blocking and is the source of …
Technically speaking it duplicates, or copies, stderr onto stdout. Usually you don’t need the exec to perform this. A more typical use of exec with file descriptors is to indicate that you want to assign a file to an unused file descriptor, e.g. exec 35< my_input BTW Don’t forget that the sequence of declaration when …
If you want to provide the pattern through a variable, you need to use ~ to match against it: awk -v pat=”$pattern” ‘$0 ~ pat’ In your case, the problem does not have to do with -F. The problem is the usage of /pat/ when you want pat to be a variable. If you say …
How about this? If you want the actual exit code … #!/bin/sh set -e cat /tmp/doesnotexist && rc=$? || rc=$? echo exitcode: $rc cat /dev/null && rc=$? || rc=$? echo exitcode: $rc Output: cat: /tmp/doesnotexist: No such file or directory exitcode: 1 exitcode: 0
The number of seconds per day are fixed with Unix timestamps. The Unix time number is zero at the Unix epoch, and increases by exactly 86400 per day since the epoch. So it cannot represent leap seconds. The OS will slow down the clock to accommodate for this. The leap seconds is simply not existent …
Expanding upon the solution to use Node.js… Here are some examples and screenshots from a page on Command Line JavaScript. The Node REPL (Shell) If you enter node on the command line with no arguments, you’ll be in the Read-Eval-Print-Loop, or REPL for short, otherwise known as a shell. Here you can interactively enter JavaScript …
Based on @user3100381’s answer, here’s a much simpler command to get the same thing which I believe should be fairly portable: PARENT_COMMAND=$(ps -o comm= $PPID) Replace comm= with args= to get the full command line (command + arguments). The = alone is used to suppress the headers. See: http://pubs.opengroup.org/onlinepubs/009604499/utilities/ps.html
You can, but bash won’t run the subsequent commands as postgres. Instead, do: su postgres -c ‘dropdb $user’ The -c flag runs a command as the user (see man su).