37 lines
1.1 KiB
ReStructuredText
37 lines
1.1 KiB
ReStructuredText
Shell Tricks
|
|
============
|
|
|
|
How to Execute Two Processes in Parallel
|
|
----------------------------------------
|
|
|
|
We want to :command:`ping` two machines parallel. *Kapow!* can get IP addresses
|
|
from query params:
|
|
|
|
.. code-block:: console
|
|
:linenos:
|
|
|
|
$ cat parallel-route
|
|
#!/usr/bin/env sh
|
|
kapow route add '/parallel/{ip1}/{ip2}' - <<-'EOF'
|
|
ping -c 1 -- "$(kapow get /request/matches/ip1)" | kapow set /response/body &
|
|
ping -c 1 -- "$(kapow get /request/matches/ip2)" | kapow set /response/body &
|
|
wait
|
|
EOF
|
|
|
|
Calling with :program:`curl`:
|
|
|
|
.. code-block:: console
|
|
:linenos:
|
|
|
|
$ curl -v http://localhost:8080/parallel/10.0.0.1/10.10.10.1
|
|
|
|
Script debugging
|
|
----------------
|
|
|
|
Bash provides the ``set -x`` builtin command that "After expanding each simple command,
|
|
for command, case command, select command, or arithmetic for command, display the
|
|
expanded value of PS4, followed by the command and its expanded arguments or associated
|
|
word list". This feature can be used to help debugging the init programs and,
|
|
together the ``--debug`` option in the server sub-command, the scripts executed
|
|
in user requests.
|