refactor / reorganize / add some comments

1 files changed, 117 insertions, 96 deletions

diff --git a/pars.sh b/pars.sh
index 670a552..4660517 100644
--- a/pars.sh
+++ b/pars.sh
@@ -15,12 +15,121 @@
 #   You should have received a copy of the GNU General Public License
 #   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+# help function
+_parssh.usage () {
+    printf '  %s\n'\
+        "parssh: Parallel SSH orchestration in a Bash session."\
+        ""\
+        "SYNOPSIS"\
+        "parssh [-NUM] [-r|--rinput FILE] [-s|--servers FILE] [-b|--bare] [-c|--config]"\
+        "  [COMMANDS] [< SERVERS]"\
+        ""\
+        "DESCRIPTION"\
+        "  -NUM  (default: 4)"\
+        "     Number of concurrent ssh connections to maintain.  E.g. '-40'."\
+        ""\
+        "  -r FILE, --rinput FILE  (default: unset/inactive)"\
+        "     File to send as STDIN redirection on remote servers."\
+        "     (Can be used as replacement for or in conjunction with COMMANDS)."\
+        ""\
+        "  -s FILE, --servers FILE  (default: unset/inactive)"\
+        "     File to use as list of servers to run COMMANDS on."\
+        "     (Cannot be used in conjunction with a server list on STDIN)."\
+        ""\
+        "  -b, --bare  (default: unset/inactive)"\
+        "     Disable prepending of hostname to each output line returned by COMMANDS on SERVERS."\
+        ""\
+	"  -C, --savecmd  (default: unset/inactive)"\
+	"     Save the remote command line and local meta data as a header on the output."\
+	""\
+        "  -c SSH_OPTIONS, --config SSH_OPTIONS  (default: unset/inactive)"\
+        "     Comma separated list of configuration parameters to be passed to SSH via '-o' flag."\
+        ""\
+        "  -o PREFIX, --out PREFIX  (default: unset/inactive)"\
+        "     Redirect STDOUT / STDERR to PREFIX.out / PREFIX.err, respectively."\
+        ""\
+        "  -t PREFIX, --tee PREFIX  (default: unset/inactive)"\
+        "     Copy STDOUT / STDERR to PREFIX.out / PREFIX.err, respectively."\
+        ""\
+        "  COMMANDS"\
+        "     The list of commands to be executed remotely by SSH on each SERVER."\
+        ""\
+        "  < SERVERS"\
+        "     Unless '-s' flag is used, STDIN will be used as list of remote servers."\
+        "     (Deliniated by newlines)."\
+        ""\
+        "NOTES"\
+        "  Given the nature of entering passwords manually, this function will likely not be"\
+        "     very useful without properly authorized SSH keys on all SERVERS."
+    return 1
+}
+
+# text processing functions
+_parssh.host_prepend ()
+    while read -r; do
+        printf "${_parssh_prepend_host+$host: }%s\n" "$REPLY"
+    done
+
+_parssh.out () {
+    local _parssh_out_stream="$1"
+
+    while read -r; do
+        [[ "${_parssh_out_stdout}" == "true" ]] && \
+            printf "%s\n" "$REPLY"
+        [[ "${_parssh_out_file}" == "true" ]] && \
+            printf "%s\n" "$REPLY" >> "${_parssh_out_prefix}.${_parssh_out_stream}"
+    done
+}
+
+_parssh.savecmd () {
+    CMDLINE=$(fc -ln -0)
+    CMDLINE="${CMDLINE#[[:space:]][[:space:]]}"
+    printf "### ###\n"
+    printf "### %s: %s\n"\
+        date "$(date +%F@%R%z)"\
+        user "$USER($UID)"\
+	pwd "$PWD"\
+	cmdline "$CMDLINE"
+    printf "### BEGIN parssh remote commands ###\n"
+    printf "%s\n### END parssh remote commands ###\n### ###\n"\
+        "$@"
+}
+
+# fd handlers
+_parssh.serverlist_fd () {
+    [[ -z "$_parssh_servers" ]] && {
+        [[ -t 0 ]] && {
+            echo "No list of servers provided."
+            return 79
+        }
+        exec 9<&0
+    } || {
+        exec 9< <(printf "%s\n" "$_parssh_servers")
+    }
+}
+
+_parssh.serverlist_fd_close () {
+    exec 9>&-
+}
+
+# ssh workers
+_parssh.ssh () {
+    ssh -n ${_parssh_ssh_config+-o} ${_parssh_ssh_config//,/ -o } $host -- "$@"
+}
+
+_parssh.ssh_rinput () {
+    ssh -T ${_parssh_ssh_config+-o} ${_parssh_ssh_config//,/ -o } $host -- "$@"\
+        < "$_parssh_rinput"
+}
+
+# main
 parssh () {
     (( $# )) || {
         _parssh.usage
         return $?
     }
 
+    # preserve current bash options and ensure monitor (job control) is set
     local _parssh_origopts=$-
     set -m
 
@@ -95,30 +204,12 @@ parssh () {
         shift
     done
 
-    [[ -z "$_parssh_servers" ]] && {
-        [[ -t 0 ]] && {
-            echo "No list of servers provided."
-            return 79
-        }
-        exec 9<&0
-    } || {
-        exec 9<"$_parssh_servers"
-    }
+    # load list of servers on fd 9
+    _parssh.serverlist_fd
 
+    # run main command loop / capture outputs
     {
-        [[ "$_parssh_savecmd" == "true" ]] && {
-	    CMDLINE=$(fc -ln -0)
-	    CMDLINE="${CMDLINE#[[:space:]][[:space:]]}"
-            printf "### ###\n"
-	    printf "### %s: %s\n"\
-	        date "$(date +%F@%R%z)"\
-                user "$USER($UID)"\
-		pwd "$PWD"\
-		cmdline "$CMDLINE"
-	    printf "### BEGIN parssh remote commands ###\n"
-	    printf "%s\n### END parssh remote commands ###\n### ###\n"\
-	        "$@"
-        }
+        [[ "$_parssh_savecmd" == "true" ]] && _parssh.savecmd
         while read host; do
             while (( $(jobs -pr | wc -l) >= ${_parssh_concurrency:-4} )); do
                 sleep 1
@@ -130,79 +221,9 @@ parssh () {
 
     wait
 
-    exec 9>&-
-    [[ "${_parssh_origopts//[^m]/}" == "m" ]] || set +m
-}
+    # close serverlist fd
+    _parssh.serverlist_fd close
 
-_parssh.ssh () {
-    ssh -n ${_parssh_ssh_config+-o} ${_parssh_ssh_config//,/ -o } $host -- "$@"
-}
-
-_parssh.ssh_rinput () {
-    ssh -T ${_parssh_ssh_config+-o} ${_parssh_ssh_config//,/ -o } $host -- "$@"\
-        < "$_parssh_rinput"
-}
-
-_parssh.host_prepend ()
-    while read -r; do
-        printf "${_parssh_prepend_host+$host: }%s\n" "$REPLY"
-    done
-
-_parssh.out () {
-    local _parssh_out_stream="$1"
-
-    while read -r; do
-        [[ "${_parssh_out_stdout}" == "true" ]] && \
-            printf "%s\n" "$REPLY"
-        [[ "${_parssh_out_file}" == "true" ]] && \
-            printf "%s\n" "$REPLY" >> "${_parssh_out_prefix}.${_parssh_out_stream}"
-    done
-}
-
-_parssh.usage () {
-    printf '  %s\n'\
-        "parssh: Parallel SSH orchestration in a Bash session."\
-        ""\
-        "SYNOPSIS"\
-        "parssh [-NUM] [-r|--rinput FILE] [-s|--servers FILE] [-b|--bare] [-c|--config]"\
-        "  [COMMANDS] [< SERVERS]"\
-        ""\
-        "DESCRIPTION"\
-        "  -NUM  (default: 4)"\
-        "     Number of concurrent ssh connections to maintain.  E.g. '-40'."\
-        ""\
-        "  -r FILE, --rinput FILE  (default: unset/inactive)"\
-        "     File to send as STDIN redirection on remote servers."\
-        "     (Can be used as replacement for or in conjunction with COMMANDS)."\
-        ""\
-        "  -s FILE, --servers FILE  (default: unset/inactive)"\
-        "     File to use as list of servers to run COMMANDS on."\
-        "     (Cannot be used in conjunction with a server list on STDIN)."\
-        ""\
-        "  -b, --bare  (default: unset/inactive)"\
-        "     Disable prepending of hostname to each output line returned by COMMANDS on SERVERS."\
-        ""\
-	"  -C, --savecmd  (default: unset/inactive)"\
-	"     Save the remote command line and local meta data as a header on the output."\
-	""\
-        "  -c SSH_OPTIONS, --config SSH_OPTIONS  (default: unset/inactive)"\
-        "     Comma separated list of configuration parameters to be passed to SSH via '-o' flag."\
-        ""\
-        "  -o PREFIX, --out PREFIX  (default: unset/inactive)"\
-        "     Redirect STDOUT / STDERR to PREFIX.out / PREFIX.err, respectively."\
-        ""\
-        "  -t PREFIX, --tee PREFIX  (default: unset/inactive)"\
-        "     Copy STDOUT / STDERR to PREFIX.out / PREFIX.err, respectively."\
-        ""\
-        "  COMMANDS"\
-        "     The list of commands to be executed remotely by SSH on each SERVER."\
-        ""\
-        "  < SERVERS"\
-        "     Unless '-s' flag is used, STDIN will be used as list of remote servers."\
-        "     (Deliniated by newlines)."\
-        ""\
-        "NOTES"\
-        "  Given the nature of entering passwords manually, this function will likely not be"\
-        "     very useful without properly authorized SSH keys on all SERVERS."
-    return 1
+    # restore bash options if modified
+    [[ "${_parssh_origopts//[^m]/}" == "m" ]] || set +m
 }