change the output format for time command

If you are doing some scripting and using ‘time’ command, then you know sometimes it becomes difficult to capture the output as the output would be something like this:

: amit ; time ls

real    0m0.002s
user    0m0.000s
sys 0m0.001s

So, it is better to change that format. Here is simple example:

TIMEFORMAT=’real %3R user %3U sys %3S pcpu %P’ time ls
amit ;  TIMEFORMAT=’real %3R user %3U sys %3S pcpu %P’ time ls
0.00user 0.00system 0:00.00elapsed 0%CPU (0text+0data 2432max)
0inputs+0outputs (0major+109minor)pagefaults 0swaps
amit ; TIMEFORMAT=’real %3R user %3U sys %3S’
amit ; time ls
real 0.001 user 0.001 sys 0.000
amit ;
amit ; TIMEFORMAT=’TIMEOUTPUT = real %3R user %3U sys %3S’
amit ; time ls
TIMEOUTPUT = real 0.001 user 0.001 sys 0.000
amit ;

bash refer parameters from the current command

In bash you can use


to refer to any parameter from the current command, example:

mv ak amit.!#:1.txt
ls amit.ak.txt

Home grown mail scheduler with bash script and cron

If you are using Linux (Fedora/Ubuntu or anything else) then you do get a lot of tools and one of them is cron. Very very useful. Just write some script that can do the task for you, put it in cron and forget it. So, here is a home grown way to schedule mails.

First, copy this script below:

#!/bin/bash -
#          FILE:
#         USAGE: ./
#       OPTIONS: ---
#          BUGS: ---
#         NOTES: ---
#        AUTHOR: Amit Agarwal (aka), 
#      REVISION:  ---

if [[ $(wc -l $mailfile|awk '{print $1}' ) -ge 5 ]]
    to=$(grep ^To: $mailfile|sed 's/To: //')
    echo "Good to send mail... to = $to"
    sendmail -t <$mailfile
    echo "once mail is send, delete the contents of file"
    echo "sed -i '4,$ d' $mailfile"

Now, create a file called mail in your home directory, with the following contents:

To: Email
From: Email
Subject: Test mail from script.

Put the first script in cron to run every minute. And whenever you want to schedule a mail, create your mail in plaintext and then schedule that with at command to be appended to the ~/mail file. As soon as that file is appended, it will be sent out in 1 min 🙂



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