A domain-specific language makes a big difference in the amount of code you write. For example, you could argue that there’s not much difference between: chmod 640 /my/file and file { “/my/file”: mode => 640, } but there’s a great deal of difference between these: FILE=/my/file chmod 640 $FILE chown foo $FILE chgrp bar $FILE … Read more
A trick I use sometimes is to use base64 to encode the commands, and pipe it to bash on the other site: MYCOMMAND=$(base64 -w0 script.sh) ssh user@remotehost “echo $MYCOMMAND | base64 -d | sudo bash” This will encode the script, with any commas, backslashes, quotes and variables inside a safe string, and send it to … Read more
If you read the man page for bash you’ll find the following at the top of the OPTIONS section: All of the single-character shell options documented in the description of the set builtin command can be used as options when the shell is invoked. In addition, bash interprets the following options when it is invoked… … Read more
I generally put something similar to the following at the beginning of every script (especially if it’ll run as a daemon): #!/bin/bash exec 3>&1 4>&2 trap ‘exec 2>&4 1>&3’ 0 1 2 3 exec 1>log.out 2>&1 # Everything below will go to the file ‘log.out’: Explanation: exec 3>&1 4>&2 Saves file descriptors so they can … Read more
bash -x script or set -x in the script. You can unset the option again with set +x. If you just want to do it for a few commands you can use a subshell: `(set -x; command1; command; …;)
You could run it silently using a Windows Script file instead. The Run Method allows you running a script in invisible mode. Create a .vbs file like this one Dim WinScriptHost Set WinScriptHost = CreateObject(“WScript.Shell”) WinScriptHost.Run Chr(34) & “C:\Scheduled Jobs\mybat.bat” & Chr(34), 0 Set WinScriptHost = Nothing and schedule it. The second argument in this … Read more
You can turn off history substitution using set +H.
There are several differences. In my opinion, a few of the most important are: [ is a builtin in Bash and many other modern shells. The builtin [ is similar to test with the additional requirement of a closing ]. The builtins [ and test imitate the functionality /bin/[ and /bin/test along with their limitations … Read more
This will return true if a variable is unset or set to the empty string (“”). if [ -z “${VAR}” ];
For reading through a symlink1, which is usually not what you want (you usually don’t want to confuse the user this way), try: IMO, that’ll produce confusing output. “I ran foo.sh, but it’s saying I’m running bar.sh!? Must be a bug!” Besides, one of the purposes of having differently-named symlinks is to provide different functionality … Read more