Hi, all:
I don't know if this is the right list to ask this question. But since I didn't
find a bash script mail list and you guys are always so helpful, then...
Here are an excerpt of a bash script:
-------------------------------------------------------
#!/bin/bash
# saveLogs.sh - Bourne Again Shell script
...
#
# FindAndSaveCoreFiles()
# Search the entire filesystem for corefiles, saving each in
# $SAVE_DIR. On Linux, we only need to search in ESS_LOG_DIR.
#
CollectCoreFiles()
{
local NEWNAME=""
local NCOREFILES=0
local OS=`uname`
if [ "$OS" == "Linux" ]; then
...
else
#
# find each corefile, record in $CORELOG, and move to a uniquely
# named file in $SAVE_DIR
#
# Look for files named "core" (Lynx default)
#
find / -type f -name core -print | while read COREFILE ; do
NCOREFILES=$[ $NCOREFILES + 1 ] # a bit strange - xq
echo $NCOREFILES # xq
NEWNAME="${HOSTNAME}esscore${NCOREFILES}_${TIMESTAMP}"
# record mapping so people can go back and figure out
# where they came from
echo -e $NEWNAME " was " `ls -l $COREFILE` >>
$SAVE_DIR/$CORELOG
mv $COREFILE $SAVE_DIR/$NEWNAME
echo "There are $NCOREFILES core files." # xq
done
fi
# What confused me most is the value $NCOREFILES outside
# the do-while loop (but still in this function) reverted
# back to its initial value, which seems contradictory to
# our concept of local variables. - xq
#echo $NCOREFILES
return 0
}
-------------------------------------------------------
The purpose of this script is to find the core files in the system and move
them to elsewhere for later analysis.
I am confused about the following issues:
1. The way of incrementing the variable NCOREFILES. Why does it use the formula
of "NCOREFILES=$[ $NCOREFILES + 1 ]",
and not the direct way of "NCOREFILES=$NCOREFILES+1"?
2. What confused me most is the value of the variable NCOREFILES ($NCOREFILES).
Say there is just 1 core file, then because the initial value of NCOREFILES is
0, it will be incremented to 1. Yes, this is the value in the do-while loop.
But outside the loop and if-block, the value of NCOREFILES is reverted back to
0 - its initial value.
It is a local variable, so any modification to it should be valid as long as we
are still in the scope of the function, right? I am really lossed at this
phenomenon.
Looking forward to any possible help,
thanks,
Xu Qiang
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