Complex grep command

[panchpan]

Hello.
Could you please help me in understanding what below commands would do - I get lost somewhere:

1)
grep -q $prebase `awk '{ if (/DB\.pf/)
{ ncol=split($2,tab,"/"); printf("%s ",tab[ncol]) } }' *SV.pf`

2)
probkup $base $OPTION /dev/null -estimate -vs $vol_size|
awk -v nombkup=$ARCH_BKUP/$nombkup '{
if (/volumes are req/) nbvol=10}
END { for(i=1;i printf("%s.%d.bkp\n",nombkup,1+i) }' > $ARCH_BKUP/VOL.BKP
NBVOL=`awk 'END { print NR+1 }' $ARCH_BKUP/VOL.BKP`


Thank you!

[Peter Nikitka]

Hi,

1) part1:
awk '{ if (/DB\.pf/) ... ' *SV.pf
Examines files *SV.pf for lines containing 'DB.pf'.
part2:
ncol=split($2,tab,"/"); printf("%s ",tab[ncol])
Takes the second field, which seems to be a pathname, extracts and prints the pure base filename.
part3: grep -q $prebase ``
Sets just a return value if $prebase is found in the above printed filenames

2 (which is not a grep and seems not really reasonable to me :-)
part1:
Analyses the output of the commamd 'probkup',
if it contains the string 'volumes are req'.
part2:
If that is true, 9 lines are printed to a file of the format (variables expanded)
$ARCH_BKUP/$nombkup.2.bkp
...
$ARCH_BKUP/$nombkup.10.bkp
part3:
Variable NBVOL is set to the number of lines of this file +1.
The result will be 1 (no match in part1) or 10 (any number of matches in part1).

mfG Peter

[panchpan]

Hello.

Could you also please help me in understanding below command :

if ! tar xf $SOURCE `tar tf $SOURCE | grep '^ipasii'`
then
echo "not success"
fi

Thank you!

[Peter Nikitka · Accepted solution]

Hi,

regarding your tar:
part1) .. `tar tf ... | grep '^..'`
The command in the backtics lists the content of $ARCHIVE and filters out filenames starting with 'ipasii'

part2) tar xf ``
The above filename are fed into tar for restore

part3) if ! tar
If the tar failes, an error message is echoed.

CAUTION:
There will be no message or error reported, when NO name of the form of part1 is found in the tar archive: Having write access to the target, all files of the archive would be extracted!
I don't think, the writer of this piece of code intended this to do ...

mfG Peter