mv fails for 1000 files

I'm trying to rename 1000 files with extension *.nc to *.txt.

When I say
mv *.nc *.txt

It fails. It says
ksh: /bin/mv: arg list too long

Why does this happen and how to resolve it.?
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prashant_n_mhatreAsked:
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gstoddartCommented:
The reason it says the command is too long is there is a system setting called MAXPATHLEN.  Anyplace between 1K and 4K (Depending on system).  No command line can exceed that value.  You apparently did.

The command "mv *.nc *.txt" is definitely not the command you want since with multiple arguments, the last argument better be a directory.  (mv = move, renaming is a side effect)

You'll probably need to write a script that does it a little more exhaustively.  The following is a SAMPLE which works by making a few naive assumptions.  You would probably need to modify it if you had files that all looked like "aaaa-123456789.nc".

#!/bin/sh
#
# Change file extension of a group of files in a named dir

if [ $# -ne 3 ]; then
    echo "Usage:  rename_files dir suffix_1 suffix_2"
    exit 1
fi

TARGET_DIR=$1
SUFFIX_1=$2
SUFFIX_2=$3

cd $TARGET_DIR
for prefix in 0 1 2 3 4 5 6 7 8 9 a b c d e f g h i \
    j k l m n o p q r s t u v w x y z
do
    list=""
    list=`ls $prefix*.$SUFFIX_1 2>/dev/null`
    for file in $list
    do
        mv $file `basename $file $SUFFIX_1`$SUFFIX_2
    done
done
#EOF



Cheers
0
 
OtetelisanuCommented:
#!/bin/sh
#
for file in `ls *.nc|cut -d. -f1`
do
mv $file.nc $file.txt
done

This script run
in the same directory
with file *.nc
and mv sequential.
0
 
OtetelisanuCommented:
#!/bin/sh
#
for file in `ls *.nc|cut -d. -f1`
do
mv $file.nc /dir/$file.txt
done

This script run
in the same directory
with file *.nc
and mv sequential.
0
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ahoffmannCommented:
ls *.nc|sed -e ' s#\(.*\)\.nc#mv & \1.txt#'|sh
0
 
prashant_n_mhatreAuthor Commented:
gstoddart:

>> (mv = move, renaming is a side effect)

Does Unix have any special command for renaming? (like 'ren' on DOS)
0
 
gstoddartCommented:
Nothing portable.  Depending on your flavour of UNIX, there could be something defined for it.  There could be some file-manager type application which knows how as well.

Other than little shell hacks like I posted, I'm not aware of a really portable way to do what you're asking.

Either way, from a command line you stil have the max command line restriction, which is probably going to be shorter than the combined names of 1000 files.

Cheers

0
 
prashant_n_mhatreAuthor Commented:
Thank you all !!!
0
 
pluimCommented:
find ./ -name "*.nc" | xargs -i basename {} ".nc" | xargs -i mv {}.nc {}.txt

This will find all files ending in .nc in the current directory, strip off the .nc extenstion (to get the base name xxxx), and then rename xxxx.nc to xxxx.txt

By using find and xargs, you avoid the shell limitation on the length of the arguments.
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