Amit Agarwal Linux Blog

Quick tip to change parameters in different files

2010-03-16 1 min read Linux
for i in *.cfg; do mv $i $i.bak;sed \’s/a/b/\’ $i.bak > $i; done

The above command is very useful to change certain regular expressions in couple of files in one directory. This can be used in variety of ways to achieve a lot of things which would normally take some time to do manually.

Bash Linux Sed

Some bashrc shorcuts for faster and profiecient directory browsing.

2010-03-10 1 min read Bash Linux

Here are some of the funtions that I have in my bashrc to make my life simple. They are not written by me but mostly taken from other places, but modified by me to some extent to suit my needs. If you know the original creator of these, let me know so I can add the attribution for the same.

This one is very useful.

.. (){
local arg=${1:-1};
local dir=””
while [ $arg -gt 0 ]; do
dir=”../$dir”
arg=$(($arg – 1));
done
cd $dir >&/dev/null
}

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Bash Tips

Bash script to view log and config file in different server and paths.

2010-03-09 1 min read Bash

I was working on a project, where I need to open file from different servers and different paths. I do it with the command:

vim ftp://username@server/path/filename

This is okay when the path is short but when the path gets longer and I have different config files to open from the same path or their associated logs, then it becomes un-necessary typing. So, I did the following:

Have a file with some aliase’s like the below and source it from the bashrc file:

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Bash

create SQL-statements from textfile with awk

2010-03-08 1 min read Linux

<a href="http://feedproxy.google.com/~r/Command-line-fu/~3/lz9uEhVxEEk/create-sql-statements-from-textfile-with-awk">create SQL-statements from textfile with awk

  <td>
    <div class="text codecolorer">
      $ $ awk \'{printf "select * from table where id = %c%s%c;\\n",39,$1,39; }\' inputfile.txt
    </div>
  </td>
</tr>
1

inputfile.txt is a space-separated textfile, 1st column contains the items (id) I want to put into my SQL statement.

39 = charactercode for single tick \’ 

    <td>
      <div class="text codecolorer">
        1 = first column
      </div>
    </td>
  </tr>
</table>

If inputfile.txt is a CSV-file separated by \”,\” use FS= to define your own field-separator:

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Bash Command One Liner Sql

Bash histoy – common history in different terminals

2010-03-04 1 min read Bash Linux

I have been looking to do this for sometime. The bash history is per
session basis and the last session to quit overwrites the bash_history
file and thus all other terminals started between the time last terminal
lasted does not get to write the commands in the history file. Secondly
the history gets cluttered with lot of duplicate entries and entries
with ls and cd commands. So finally I added these to the bashrc file:

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Bash Bashrc Fedora Linux

Bash Sub Shells

2010-03-02 1 min read Bash

Taken from <a href="http://www.linuxjournal.com/content/bash-sub-shells" target="_blank">here.

<span class=\"c\">#!/bin/bash</span>

<span class="nv">server_cmd</span><span class="o">=</span>server <span class="nv">pid_file</span><span class="o">=</span><span class="k">$(</span>basename <span class="nv">$server_cmd</span> .sh<span class="k">)</span>.pid <span class="nv">log_file</span><span class="o">=</span><span class="k">$(</span>basename <span class="nv">$server_cmd</span> .sh<span class="k">)</span>.log

<span class="o">(</span> <span class="nb">echo</span> <span class="s2">"Starting server"</span> <span class="nb">echo</span> <span class="s2">"Doing some init work"</span> <span class="nv">$server_cmd</span> <span class="c"># server becomes a daemon</span>

&lt;span class=\"k\">while &lt;/span>&lt;span class=\"nb\">true&lt;/span>

<span class="nb"> </span><span class="k">do</span> <span class="k"> if</span> <span class="o">[[</span> -f <span class="nv">$pid_file</span> <span class="o">]]</span>; <span class="k">then</span> <span class="k"> </span>sleep 15 <span class="k">else</span> <span class="k"> </span><span class="nb">break</span> <span class="nb"> </span><span class="k">fi</span> <span class="k"> done</span> <span class="k"> </span>mail -s <span class="s2">"Server exitted"</span> joe@blow.com <<<CRAP

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Bash Linux Shell

bash script with sql to get the number of records from multiple tables.

2010-02-10 1 min read Bash Database Learning Linux Solaris

Here is the bash script:

#!/bin/sh
names[1]=errorlog
names[2]=amit1log
names[3]=amit2log
names[4]=amit3log
names[5]=amit4log
j=1
echo $1
for i in $( sqlplus amit/passwd@tns @get_count.sql |sed  -n &#8217;/COUNT/,/Disconnected/p&#8217;|sed &#8217;/COUNT/ d&#8217;|sed &#8217;/—/ d&#8217;|sed &#8217;/Disconnected/ d&#8217;|tr &#8217;n&#8217; &#8217; &#8217;  )
do
temp=${names[$j]}
let count=30-${#temp}
for ((I=1; I <= $count ; I++))
do
printf &#8221; &#8221;
done
echo  &#8221;${names[$j]}    : $i&#8221;
# echo $j
let j=j+1
done
echo
echo

and the required sql script:

select count() from errorlog;
select count() from amit1log;
select count() from amit2log;
select count() from amit3log;
select count(*) from amit4log;
quit;

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Bash Oracle Script Solaris Sql
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