sreda, 14. november 2012

Running sudo command without password

What I found out is that running a command using sudo without entering password there are two options:

  • echo PASSWORD | sudo -S COMMAND
  • adding following lineto /etc/sudoers:
Please note that this has to be after all group definitions.
You can check what sudo priviliges you have using
sudo -l
For this case this gives:
This means that all command require password except for the COMMAND. If we would put the username definitin before group definitions sudo -l would give:
This would still require password for all commands.

sreda, 07. november 2012

Find where code was changed in Mercurial

If you want to find out in which revisions a piece of code was changed then you can use a Mercurial command something like this:

hg grep --all PIECE_OF_CODE | awk 'BEGIN {FS=":"} {print $1" "$2}' | uniq
and you will get back a list of files with coresponding revisuin numbers:
repo/src/java/com/kovica/ 30
repo/src/java/com/kovica/ 10

torek, 06. november 2012

Remove empty lines from a file on Linux using command line

This one is especially useful when searching through Glassfish's log files.
There are many ways you can remove empty lines from a file:

  • awk 'NF' file
  • sed '/^$/d' file
  • grep "^$" -v file
  • grep . file
  • egrep "^[[:space:]]?$" -v file
  • perl -n -e 'print unless /^\s*$/' file
And I'm sure there are many more. :)