B-shell tips

Change separators for a sequence of for-in statement

A reserved variable IFS (Internal Field Separator) defines a set of characters of separators for a sequence of for-in statement. For example, configure the variable as follows if you want to split a sequence by ",", by neither any whitespaces nor line breaks.

$ export IFS=','

A usage example is shown below.

$ IFS=','; for x in `echo 'a,b,c'`; do echo $x; done
a
b
c

mailout.sh — Notifying command completion with the exit status via E-mail

The following code is a shell script that notifies you the command completion with the exit status via E-mail. You can also download the source code from the link mailout.sh.


#!/bin/sh



#

# $Id: mailout.sh,v 966c5717bd73 2011/01/20 13:53:16 Hirochika $

#

# Copyright 2011 Scyphus Solutions Co. Ltd.  All rights reserved.

# Authors:

#      Hirochika Asai

#



if [ -z "$1" -o -z "$2" ];

then

   echo "Usage: $0  " >& 2

   exit 1

fi

mailaddr=$1

cmd=$2



args=""

num=3

while [ $num -le $# ];

do

    a0=`eval echo \$\{$num\}`

    a2=`echo ${a0} | sed -e "s/\ /\\\\\ /g"`

    args="${args} ${a2}"

    num=`expr $num + 1`

done



eval ${cmd} ${args}



ret=$?



## Mail the result

dt=`LC_ALL=C date`

printf "The following command exits with status ${ret}:\n\$ ${cmd} ${args}\n@${dt}\n" | mail -s "Command completion notification (${dt})" "${mailaddr}"

The following command is a usage example:

$ ./mailout.sh notify@example.jp sleep 3600

In this example, after 3600 seconds (i.e., 1 hour), this command notifies the exit status code to the email address <notify@example.jp>.