Tag Archives: shell

Commonly used daily Linux Commands.

1) How to Replace a big string with WildCard Characters.  just dump the string in between the hash (#) and  it does the job.  use /g at the end to replace strings everywhere.


2) Search for a word and delete to the end of the line.  for ex: in an XML file  sometimes you need to delete 1000’s of lines matching a word or a <string> spread across the XML file,  you can’t simply replace some lines like below ex.. in MS-WORD or any other editors,   from the below ex: only delete those which starts with <pcode> until the end of the line and preseve the “\>”. use the below simple command to do the job.

<xml=? >
<scalar variable   <pcode  value=1000  test1 test3 test4> />
<vector variable   <pcode  value=1001  test5 test6 test7> />
<stellar value       <pcode  value=1002  test8 test9 test10> />


3)  How to find Un-wanted files, if you’r clean folder has been messed up.  I had this situation where some of the junk files has been added to my MySql Data direcotory where i see only the Database Tables which are useful and i used the below command to find all the files excluding MySql Database Tables.

grep ./ --exclude=*.{ibd,MYD,MYI,frm} *

4)  CHOP the file to 1gb from a 9.5GB file : i had this big file which is 9.5gb Data MySql Log file for my analysis purposes, however my script takes too long time to read this file and i had no choice to chop this file to 1GB and read the data from this 1GB file which makes it easier for MySql to read faster.  I used the below command.

 dd if=10gbfilename of=1gb_new_filename bs=100M count=10

5)  How to get extract 100 lines of data from a file which has 10,000 lines.
sed -n 1,100p test1.log > outputfile.log
6) How to find which raid your Linux software has..

for i in /dev/md*; do printf ‘%s: %s\n’ $i “$( sudo /sbin/mdadm –detail $i 2>/dev/null | grep ‘Raid Level’ )”; done

7) Convert files to Unix &  UTF8 format.

Convert to UTF8 format

/usr/bin/iconv -c -f LATIN1 -t UTF8 insert_statements_postgres1.sql > utf8_postgres_inserts.sql

/usr/bin/iconv -c -f LATIN1 -t UTF8 delete_statements_post1.sql > utf8_postgres_deletes.sql

Convert Bulk files to utf8 format: (csv files)

for file in *.csv; do
/usr/bin/iconv -c -f LATIN1 -t UTF8 “$file” -o “${file%.csv}.csv”


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