How to insert a character in a delimited chain

echo “e_ff_0123_1″ | awk -F_ ‘{print $1″_”$2″_”$3″_0″$4}’

Select the end of a chain

#:~$ toto="bonjour le monde"
#:~$ echo ${toto:$((${#toto}-10))}
r le monde

${var:x} : extract sub chain of $var from char n° x to the end.
$((….)) : allow to do calculation

Create a multi tar with specified size

Create a tar file:

tar cvf - gaim/ | split -b 1024k - gaim.tar
ll gaim.tar*
-rw-r--r--    1 root     root      1048576 Jan 29 16:57 gaim.taraa
-rw-r--r--    1 root     root      1048576 Jan 29 16:57 gaim.tarab
-rw-r--r--    1 root     root      1048576 Jan 29 16:57 gaim.tarac
-rw-r--r--    1 root     root      1048576 Jan 29 16:57 gaim.tarad
-rw-r--r--    1 root     root      1048576 Jan 29 16:57 gaim.tarae
-rw-r--r--    1 root     root       225280 Jan 29 16:57 gaim.taraf

To read it :

cat gaim.tar* | tar tvf -

SIZE may have a multiplier suffix: b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024, GB 1000*1000*1000, G 1024*1024*1024, and so on for T, P, E, Z,Y.