this error a got through mysql command line:

mysql> delete from groups where `group_id`=4;
ERROR 1030 (HY000): Got error -1 from storage engine

It is mysql’s error log:

Cannot delete/update rows with cascading foreign key constraints that exceed max depth of 250
If you use 5.1.51- Just update your mysql-server version.
This is bug of mysql-server-5.1.51 – after:
#portupgrade mysql-server

problem disappeared.

Batch converting files from folder:

#mkdir new; for a in $(find . -name "*.php"); do iconv -f KOI8-R -t utf-8 <"$a" >new/"$a" ; done

It will make “new” directory with converted files.

Create dump of mysql base:

# mysqldump -uDBUSER -pPASSWORD DBNAME > filename.sql

or
# mysqldump --user=username --password=password DBNAME > filename.sql

if you need to make dump of a few databases you can use parametr -B (or –databases):

mysqldump -uDBUSER -pPASSWORD -B DBNAME1 DBNAME2 > filename.sql

Make dump of the all Databases on host:
mysqldump -uDBUSER -pPASSWORD -A > filename.sql

If you need only dump structure of database (without data):

mysqldump -uDBUSER -pPASSWORD --no-data DBNAME > filename.sql

If you want to make limited by records mysqldump, next command especially for you (It was really cool command when I need dump and then move test copy of project with enormous mysql database):

mysqldump -uDBUSER -pPASSWORD --where="true limit 100" DBNAME > filename.sql

this command will dump your database with defined amount records in each table.

Perl: Premature end of script headers

A long time I have tried to fix it by sending headers like:

print "Content-type: text/plain\n\n"; но безуспешно.

The problem was just in DOS newline format. Just need change format from DOS/WIN (CR/LF) to Unix (LF).

I hope it will help somebody else.