From f18200bf1b9b9d1a3f2ad042672542655477ba98 Mon Sep 17 00:00:00 2001
From: Tom Scavo <trscavo@internet2.edu>
Date: Sat, 17 Jun 2017 16:37:59 -0400
Subject: [PATCH] Add options for HEAD requests and HTTP Compression
---
bin/cget.sh | 52 +++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 41 insertions(+), 11 deletions(-)
diff --git a/bin/cget.sh b/bin/cget.sh
index a3d2539..d8d6487 100755
--- a/bin/cget.sh
+++ b/bin/cget.sh
@@ -29,7 +29,7 @@ display_help () {
server responds with 304 Not Modified, the cached resource
is output instead.
- Usage: ${0##*/} [-hvq] [-F | -C] URL
+ Usage: ${0##*/} [-hvqFCIx] URL
This script takes a single command-line argument. The URL
argument is the absolute URL of an HTTP resource. The script
@@ -39,24 +39,41 @@ display_help () {
Options:
-h Display this help message
-v Log verbose messages
- -q Log no messages
- -F Enables "Force Output Mode"
- -C Enables "Cache Only Mode"
+ -q Log no messages other than warnings or errors
+ -F Enable "Fresh Content Mode"
+ -C Enable "Cache Only Mode"
+ -I Enable "Header Only Mode"
+ -x Enable "Compressed Mode"
Option -h is mutually exclusive of all other options.
The default behavior of the script is modified by using
- option -F or -C, which are mutually exclusive. Force Output
- Mode (option -F) forces the return of a fresh resource. The
- resource is output on stdout if and only if the server
- responds with 200. If the response is 304, the script silently
- fails with exit code 1.
+ option -F, -C, or -I. Options -F and -C are mutually exclusive
+ of each other. Option -I may be used with option -C (but not
+ with option -F).
+
+ Fresh Content Mode (option -F) forces the return of a fresh resource.
+ The resource is output on stdout if and only if the server responds
+ with 200. If the response is 304, the script silently fails with
+ status code 1.
Cache Only Mode (option -C) bypasses the GET request altogether
and goes directly to cache. If the resource resides in cache,
it is output on stdout, otherwise the script silently fails
with exit code 1.
+ Header Only Mode (option -I) issues a HEAD request instead of a GET
+ request, in which case, only the response headers are returned in the
+ output. Note that nothing is written to cache when option -I is used.
+
+ Compressed Mode (option -x) enables HTTP Compression by adding an
+ Accept-Encoding header to the request; that is, if option -x is
+ enabled, the client merely indicates its support for HTTP Compression
+ in the request. The server may or may not compress the response.
+
+ Important! This implementation treats compressed and uncompressed
+ requests for the same resource as two distinct resources.
+
ENVIRONMENT
This script leverages a handful of environment variables:
@@ -82,8 +99,15 @@ display_help () {
\$ url=http://md.incommon.org/InCommon/InCommon-metadata.xml
\$ ${0##*/} \$url # Retrieve the resource using HTTP conditional GET
- \$ ${0##*/} -F \$url # Enable Force Output Mode
+ \$ ${0##*/} -F \$url # Enable Fresh Content Mode
\$ ${0##*/} -C \$url # Enable Cache Only Mode
+ \$ ${0##*/} -x \$url # Enable Compressed Mode
+
+ Note that the first and last examples result in distinct cached
+ resources. The content of a compressed resource will be the
+ same as the content of an uncompressed resource but the headers
+ will be different. In particular, a compressed header will include
+ a Content-Encoding header.
HELP_MSG
}
@@ -136,7 +160,7 @@ http_tools.sh"
#######################################################################
help_mode=false; local_opts=
-while getopts ":hvqFC" opt; do
+while getopts ":hvqFCIx" opt; do
case $opt in
h)
help_mode=true
@@ -154,6 +178,12 @@ while getopts ":hvqFC" opt; do
C)
local_opts="$local_opts -$opt"
;;
+ I)
+ local_opts="$local_opts -$opt"
+ ;;
+ x)
+ local_opts="$local_opts -$opt"
+ ;;
\?)
echo "ERROR: $script_name: Unrecognized option: -$OPTARG" >&2
exit 2