how to reduce a large file

[Ignacio Rodríguez Arrós]

I have a 55Mg file in oracle (alert_baan.log) and i want to reduce it by supressing the 1000000 first lines.Witch command must i used?
(Sorry for my english, i hope you'll understand it)

[Steve Steel]

Hi

Copy it to another name and then use
tail +n 1000001 newfile > oldfile
rm newfile


see man tail


Steve Steel

[Pierce Byrne_1]

tail +100000 file > file.new
mv file.new file

[Stefan Farrelly · Accepted solution]

The alert log is constantly being help open/possibly written to so I dont think you want to rm it. Simply null it out by doing;
cat /dev/null >alert_baan.log

This will make the logfile 0 bytes in size but not remove it so that any running processes using this logfile can still use it.

[Ravi_8]

Hi

#tail +n 1000000 file > newfile
#mv newfile file

should do the job

[James Beamish-White]

Hiya,

Yes, the commands (as stated above) are:

tail +1000000 alert_baan.log > myfile
mv myfile alert_baan.log

I would put it in a script so as to minimise the time between commands, otherwise you might overwrite some logs that are added to the end of the original file before you mv the new file over it.

Cheers!
James

[Kenneth_19]

This method also works:

# sed -n '1000000,$ p' alert_baan.log > new_file
# mv new_file alert_baan.log

Regards,
Kenneth

[Justo Exposito]

Hi Ignacio,

You can do it by using ed, in order to do it try this:
echo "1, 1000000 d\nw" | ed alert_baan.log

Hope this helps you,

Justo.

Deber??as adjudicar puntos a las soluciones que te dan, esas son las reglas y recomendaciones del foro y si no lo haces podr??as dejar de obtener ayuda.

[Bill McNAMARA_1]

split has a line option also, and can be useful for large file operations..

Later,
Bill

[Ignacio Rodríguez Arrós]

Justo, he entrado a ver las respuestas 4 veces y las cuatro veces he asignado puntos, luego pincho en submit, espero a que salga la siguiente pantalla y cierro el explorador, pero he observado que cuando vuelvo a entrar, los punto no aparecen, sigue a pareciendo el boton para asignarlos. Lo siento pero no se lo que hago mal para que no aparezcan. Si me indicais c??mo hacerlo correctamente vuelvo a a signarlos. A Y gracias a todos, todas las soluciones son validas aunque he usado la de cat /dev/nul >

[Nick Wickens]

I use csplit to housekeep log files - Attached is a script I use which maintains only the last few weeks of my aplications log directories. Because the application does not write a regular datestamp in the log I force one by running this everynight at midnight.

ERRORLOG=/opt/ROBIN/log
for LOGNAME in $(ls $ERRORLOG | grep rerr)
do
date +Logday=%.1j >> $ERRORLOG/$LOGNAME
done

The script attached is then run 30 minutes later.

[Nick Wickens]

Translation courtesy of altavista

Just, I have entered to see the answers 4 times and the four times I have assigned points, soon thorn in submit, hope to that it leaves the following screen and I close the explorer, but have observed that when I return to enter, them point do not appear, follows seeming the button to assign them. I feel it but not what I make bad so that they do not appear. If me indicais how to do it correctly I return to a to sign them. To and thanks to all, all the solutions are been worth although I have used the one of cat/dev/nul >

[Nick Wickens]

Heres the script that failed to attach earlier (hopefully !)

[Nick Wickens]

Ok third time lucky - heres the script (please please please appear this time !)