bash tips and tricks

10/6/2016 - 8:44 PM

Execute but Keep the Current Working Directory

following code changes cwd to ./step1

cd step_1
./build.sh
./test.sh

adding braces gets the code executed w/o affecting the cwd

(cd step_1 && ./build.sh && ./test.sh)

The bash Variable Index, don't expect info, just index.

Informal and meaningful illustration is following

$1, $2, $3, ... are the positional parameters.
"$@" is an array-like construct of all positional parameters, {$1, $2, $3 ...}.
"$*" is the IFS expansion of all positional parameters, $1 $2 $3 ....
$# is the number of positional parameters.
$- current options set for the shell.
$$ pid of the current shell (not subshell).
$_ most recent parameter (or the abs path of the command to start the current shell immediately after startup).
$IFS is the (input) field separator.
$? is the most recent foreground pipeline exit status.
$! is the PID of the most recent background command.
$0 is the name of the shell or shell script.

Formal and more lengthy illustration is following