2.140

examples/sync_parallel_unix.sh

@@ -1,6 +1,11 @@
 #!/bin/sh
 #
-# $Id: sync_parallel_unix.sh,v 1.7 2018/12/06 10:09:03 gilles Exp gilles $
+# $Id: sync_parallel_unix.sh,v 1.9 2021/02/19 13:41:51 gilles Exp gilles $
+
+# If you're on Windows there is a possibility to install and use parallel
+# but I have never tested it. I found:
+# https://stackoverflow.com/questions/52393850/how-to-install-gnu-parallel-on-windows-10-using-git-bash
+
 
 # Example for imapsync massive migration on Unix systems.
 # See also http://imapsync.lamiral.info/FAQ.d/FAQ.Massive.txt
@@ -12,8 +17,11 @@
 # in the while loop below.
 # # Each line contains 6 columns, columns are parameter values for 
 # --host1 --user1 --password1 --host2 --user2 --password2
-# and a trailing empty fake column to avoid CR LF part going 
-# in the 6th parameter password2. Don't forget the last semicolon.
+#
+# Extra columns can be used to pass extra parameters but the script reading
+# this file have to read them into some variables.
+#
+# Last, don't forget the last semicolon.
 #
 # You can add extra options after the last line 
 # Use character backslash \ at the end of each supplementary line, except for the last one.
@@ -22,32 +30,93 @@
 # The credentials filename "file.txt" used for the loop can be renamed 
 # by changing "file.txt" below.
 
-# The part 'echo {1} | egrep "^#" > /dev/null ||' is just there to skip commented lines in file.txt
-# It can be removed if there is no comment lines in file.txt
+# Now I explain what come next, the actual stuff, which is barely 
+# a single long command line written on several lines for the reading 
+# convenience
 
+# The first word is the parallel command itself, it's a perl utility 
+# written by Ole Tange, available on Linux systems, already packaged. 
+# It is also called GNU Parallel. The GNU Parallel homepage is
+# https://www.gnu.org/software/parallel/
+# Parallel is very powerful, you could easily distribute the parallel stuff
+# on remote machines with it (not used here).
+
+# The parallel command is then followed by its parameters.
+# parallel parameters explained:
+#
 # --max-procs 7 means parallel will parallelize up to 7 jobs at a time,
 # adjust this value by monitoring your system capacity.
+#
+# --delay 1.1 means parallel will pause 1.1 seconds after starting each job.
+#
+#  --colsep ';' means the separator between values is the character semi-colon ;
+# 
+# --arg-file file.txt means the actual input file is named file.txt
+# 
+# --line-buffer means outputs will be of whole lines instead of a big mess
+#  of part of them for the different processes. One line belongs to one process.
+# 
+# --tagstring "from {2} to {5} : " mean that each line will begin with the 
+# words "from {2} to {5} : " where {2} will be replaced by the second column
+# and {5}  will be replaced by the fifth column. Hack this part as you wish
+
+
+# The remaining parameters is the command to be executed by the parallel 
+# command, ie, the command to be run several times in parallel with 
+# different parameters each time. 
+
+# Some explanations about this remaining parts.
+#
+# The part 'echo {1} | egrep "^#" > /dev/null ||' is just there to skip 
+# commented lines in file.txt
+# It can be removed if there is no comment lines in file.txt
+
+# The part $DRYRUN is a variable that can be either the echo command
+# or nothing. It is a trick to permit you to see the command and its 
+# parameters without running it
+# 
+
+# {1} will be replaced by the first column in file.txt 
+# {2} will be replaced by the second column in file.txt 
+# {3} will be replaced by the third column in file.txt 
+# ...
+
+
+# "$@" will be replaced by the parameters of this script itself,
+# the one you are reading now. It's usefull if you want to
+# add temporarly a parameter for all runs without editing any file.
+# For example, 
+#   sync_parallel_unix.sh --justlogin 
+# will run all imapsync with the --justlogin parameter added.
+
+# --simulong 5 is just there to show that you can also add parameters
+# here and that you have read this section. --simulong 5 does nothing
+# else than printing "Are you still here ETA: xx/25 msgs left"
+# five times per second. It will show the living output of all
+# paralelized runs
 
-# --delay 2 means parallel will pause 2 seconds after starting each job.
 
 check_parallel_is_here() {
         parallel --version > /dev/null || { echo "parallel command is not installed. Install it first."; return 1; }
 }
 
+# First, there is no need to go further if the parallel command is not avalable
+# one the current system.
+
 check_parallel_is_here || exit 1 ;
 
 echo Looping with parallel on account credentials found in file.txt
 echo
 
+
 DRYRUN=echo
 # Comment the next line if you want to see the imapsync command instead of running it
+# since the previous echo value will be discarded
 DRYRUN=
 
-parallel --max-procs 7 --delay 2 --colsep ';' --arg-file file.txt --line-buffer --tagstring "from {2} to {5} : " \
+parallel --max-procs 7 --delay 1.1 --colsep ';' --arg-file file.txt --line-buffer --tagstring "from {2} to {5} : " \
         'echo {1} | egrep "^#|^ *$" > /dev/null ||' \
         $DRYRUN imapsync --host1 {1} --user1 {2} --password1 {3} \
-        --host2 {4} --user2 {5} --password2 {6} 
+        --host2 {4} --user2 {5} --password2 {6} "$@" --simulong 5 
 
 
-
-# {=7=} "$@"