How to rename all files in a directory adding a prefix - linux

Question

I first create 10 digit random number
export mask=$RANDOM$RANDOM$RANDOM; let "mask %= 10000000000";
This command works well
for i in /home/testing/*; do mv "$i" "$mask$i"; done
The problem with the above command is that it only works when I am in /home/testing. As soon as I move the script, i get this error
mv: cannot move ‘/home/testing/rec001.mp4’ to ‘3960731225/home/testing/rec001.mp4’: No such file or directory
What am I doing wrong here?

Answer 1

You need to separate the path from the filename before you apply the mask. For example, to use in a script where the directory is passed as an argument to the script:
path="$1"
## Note: this assumes you are exporting mask earlier. If not, set mask here
for i in "${path}"/*; do
dir="${i%/*}" # path component
ffname="${i##*/}" # filename component
mv "$i" "${dir}/${mask}${ffname}"
done
This will apply mask to all files in the given directory, no matter where the directory is.
An example of a script that incorporates this is shown below. You can save this script wherever you like. You can either make it executable chmod 0755 scriptname or call it with bash scriptname. To use the script, add the path you want to prefix the files in as the first argument. E.g bash scriptname /path/to/files (or just scriptname /path/to/files if you made it executable):
#!/bin/bash
# validate input
[ -n "$1" ] || {
printf "error: insufficient input. Usage: %s /path/to/files\n" "${0//\//}"
exit 1
}
# validate directory
[ -d "$1" ] || {
printf "error: directory not found: '%s'\n" "$1"
exit 1
}
path="$1"
## Note: this assumes you are exporting mask earlier. If not, set mask here
## validate mask set and is 10 chars (added per comment)
[ -n "$mask" -a "${#mask}" -eq 10 ] || {
printf "error: mask '%s' either unset or not 10 characters\n" "$mask"
exit 1
}
# move files
for i in "${path}"/*; do
[ -f "$i" ] || continue # if not file, skip
dir="${i%/*}" # path component
ffname="${i##*/}" # full filename component (with .ext)
mv "$i" "${dir}/${mask}${ffname}"
done
Here is a sample of what moves would take place with the script named prefix.sh when called on the directory dat in the current working directory and when called on ~/tmp outside the current directory:
output (mask=3960731225):
$ ./prefix.sh dat
dat/f1f2.dat => dat/3960731225f1f2.dat
dat/field.txt => dat/3960731225field.txt
dat/flop.txt => dat/3960731225flop.txt
dat/hh.dat => dat/3960731225hh.dat
dat/hh1.dat => dat/3960731225hh1.dat
dat/hostnm => dat/3960731225hostnm
dat/hosts.dat => dat/3960731225hosts.dat
$ ./prefix.sh ~/tmp
/home/david/tmp/tcpd.tar.xz => /home/david/tmp/3960731225tcpd.tar.xz
/home/david/tmp/tcpdump-capt => /home/david/tmp/3960731225tcpdump-capt
/home/david/tmp/tcpdump.new.1000 => /home/david/tmp/3960731225tcpdump.new.1000
/home/david/tmp/test => /home/david/tmp/3960731225test

Answer 2

There is two commands that is quite helpful, basename and dirname.
They will give you the dir part and the filename, have a look at this test script.
#!/bin/bash
mask=$RANDOM$RANDOM$RANDOM; let "mask %= 10000000000";
echo $mask
mkdir -p testing
> testing/nisse.txt
> testing/guste.txt
> testing/berra.txt
ls testing/
for i in testing/*
do
file=$(basename $i)
dir=$(dirname $i)
newfile=$mask$file
echo $i $dir $file $newfile
mv "$dir/$file" "$dir/$newfile"
done
ls testing/
And it will output:
247639260
berra.txt gusten.txt nisse.txt
testing/berra.txt testing berra.txt 247639260berra.txt
testing/guste.txt testing guste.txt 247639260guste.txt
testing/nisse.txt testing nisse.txt 247639260nisse.txt
247639260berra.txt 247639260guste.txt 247639260nisse.txt
Please note that I wrote it very verbose to make it more clear and readable.

Answer 3

How about adding a cd command before your command now, wherever you want to move the script it works,
cd /home/testing
for i in /home/testing/*; do mv "$i" "$mask$i"; done