I want to use rsync for incremental backups. However it fails when I try it like this:
SRC="/"
TRG="/backup/"
LNK="/oldbackup/"
OPT="-a --exclude={/dev,/proc,/sys,/tmp,/run,/mnt,/media,/lost+found} --link-dest=$LNK"
rsync $OPT $SRC $TRG
But works like this:
SRC="/"
TRG="/backup/"
LNK="/oldbackup/"
rsync -a --exclude={/dev,/proc,/sys,/tmp,/run,/mnt,/media,/lost+found} --link-dest=$LNK $SRC $TRG
What did I do wrong?
Check the order of expansions in man bash: brace expansion happens first, variable expansion happens later. Therefore, braces in a variable are not expanded.
You can use an array to capture the values, use expansion already in the assignment:
opts=( -a --exclude={/dev,/proc,/sys,/tmp,/run,/mnt,/media,/lost+found} --link-dest="$LNK" )
rsync "${opts[#]}" "$SRC" "$TRG"
Related
This question already has answers here:
Bash: need help passing a a variable to rsync
(3 answers)
Closed 4 years ago.
I have the following for-loop which loops through all the given sources that need to be copied.
for i in "${sources[#]}"; do
exclude="--exclude 'exclude_folder/exclude_file'"
rsync -az $exclude $i $destination
done
However, the exclude option is not working.
for i in "${sources[#]}"; do
exclude="--exclude 'exclude_folder/exclude_file'"
rsync -az "$exclude" "$i" "$destination"
done
If I use the code above, rsync will exit and give an error that it is an unknown option.
If I simply use the following code, it works, but I want to use a variable for the exclude option.
for i in "${sources[#]}"; do
rsync -az --exclude 'exclude_folder/exclude_file' $i $destination
done
I would use eval.
Your code:
for i in "${sources[#]}"; do
exclude="--exclude 'exclude_folder/exclude_file'"
rsync -az "$exclude" "$i" "$destination"
done
would be then (I'm trying to be as close to your logic as possible):
for i in "${sources[#]}"; do
exclude="--exclude 'exclude_folder/exclude_file'"
rsync_command="rsync -az $exclude $i $destination"
eval rsync_command
done
From the eval man pages:
eval
Evaluate several commands/arguments
Syntax
eval [arguments]
The arguments are concatenated together into a single command, which
is then read and executed, and its exit status returned as the exit
status of eval. If there are no arguments or only empty arguments, the
return status is zero.
eval is a POSIX `special' builtin
EDIT
Gordon Davisson is right about the bugs/insecurities in eval. If any other solution is available then it is better to use it. Here the bash arrays are better. The array answer is superior answer.
Please see the answer at Bash: need help passing a a variable to rsync
Example list directories to exclude (also wildcharts) :
#!/bin/sh
export PATH=/usr/local/bin:/usr/bin:/bin
LIST="rootfs usr data data2"
for d in $LIST; do
rsync -az --exclude /$d/ .....
done
RSYNC="rsync -avzhe 'ssh -i /path/to/deploy_keys/id_rsa' --delete "
# Files
$RSYNC deploy#ip:/var/www/path1 /var/www/path1
$RSYNC deploy#ip:/var/www/path2 /var/www/path2
I'd like to introduce this RSYNC Variable to be more compact, but it throws an error:
Unexpected remote arg: deploy#ip:/var/www/path1
If i use only rsync inside the doublequotes, it works fine. For the sake of readability, i'd keep them separate command invocations.
I agree that eval is dangerous. In addition to the array approach #Eugeniu Rosca suggested, you could also use a shell function:
my_rsync() {
rsync -avzhe 'ssh -i /path/to/deploy_keys/id_rsa' --delete "$#"
}
my_rsync deploy#ip:/var/www/path1 /var/www/path1
my_rsync deploy#ip:/var/www/path2 /var/www/path2
BTW, you should read BashFAQ #50: I'm trying to put a command in a variable, but the complex cases always fail!.
If you want to store the command string into a variable and evaluate it later, you can use eval or an alternative safer technique:
#!/bin/bash
# Store the command into an array
RSYNC=(rsync -avzhe 'ssh -i /path/to/deploy_keys/id_rsa' --delete)
# Run the command
"${RSYNC[#]}" deploy#ip:/var/www/path1 /var/www/path1
Why eval should be avoided
After you assign a string to a variable and then submit it to shell again it is tokenized differently. Consider the following script
VAR="/bin/ls 'Test1 Test2'"
$VAR
It will throw two errors:
/bin/ls: cannot access 'Test1
/bin/ls: cannot access Test2'
You guessed it right, the apostrophes are no longer affecting tokenization. Instead they are treated as normal characters when the commandline arguments are fed to /bin/ls
While eval is rightly considered evil, it is by far the easiest way to get a script running. It stitches all the arguments into one line and applies the tokenizing procedure again.
RSYNC="rsync -avzhe 'ssh -i /path/to/deploy_keys/id_rsa' --delete "
# Files
eval $RSYNC deploy#ip:/var/www/path1 /var/www/path1
eval $RSYNC deploy#ip:/var/www/path2 /var/www/path2
I have been working on a backup script that uses rsync to do an incremental backup.
I have tested the following rsync command manually, and it runs and completes a backup without error:
rsync -aAXv --delete --progress --link-dest=/backup/Uyuk/Uyuk-backup-part1/2014-02-24/ /mnt/backup/ /backup/Uyuk/Uyuk-backup-part1/2014-02-25/
however when I run that same command in my backup script it gives me the following error:
rsync: -aAXv --delete --progress --link-dest=/backup/Uyuk/Uyuk-backup-part1/2014-02-24/ /mnt/backup/ /backup/Uyuk/Uyuk-backup-part1/2014-02-25/: unknown option
rsync error: syntax or usage error (code 1) at main.c(1422) [client=3.0.6]
I ran bash -x on my script to figure out exactly what is sent to the console and here is what was printed:
+ rsync '-aAXv --delete --progress --link-dest=/backup/Uyuk/Uyuk-backup-part1/2014-02-24/ /mnt/backup/ /backup/Uyuk/Uyuk-backup-part1/2014-02-25/'
Does anyone see what is wrong? I cant find anything that would cause the syntax error.
EDIT:
Here is the actual code I have in the script, and this is a pretty large script so yes some variables are not defined here, but you get the idea.
mkdir -p "/backup/$HOST/$NAME/$TODAY"
#source directory
SRC="$MNT"
#link directory
LNK="/backup/$HOST/$NAME/$LAST/"
#target directory
TRG="/backup/$HOST/$NAME/$TODAY/"
#rsync options
OPT1="-aAXv --delete --progress --link-dest=$LNK"
#run the rsync command
echo "rsync $OPT1 $SRC $TRG"
rsync "$OPT1 $SRC $TRG" > /var/log/backup/backup.rsync.log 2>&1
You are passing your option list as a single argument, when it needs to be passed as a list of arguments. In general, you should use an array in bash to hold your arguments, in case any of them contain whitespace. Try the following:
mkdir -p "/backup/$HOST/$NAME/$TODAY"
#source directory
SRC="$MNT"
#link directory
LNK="/backup/$HOST/$NAME/$LAST/"
#target directory
TRG="/backup/$HOST/$NAME/$TODAY/"
#rsync options
OPTS=( "-aAXv" "--delete" "--progress" "--link-dest=$LNK" )
#run the rsync command
echo "rsync $OPT1 $SRC $TRG"
rsync "${OPTS[#]}" "$SRC" "$TRG" > /var/log/backup/backup.rsync.log 2>&1
An array expansion ${OPTS[#]}, when quoted, is treated specially as a sequence of arguments, each of which is quoted individually to preserve any whitespace or special characters in the individual elements. If arr=("a b" c d), then echo "${arr[#]}" is the same as
echo "a b" "c" "d"
rather than
echo "a b c d"
This will not work in a shell that doesn't support arrays, but then, arrays were invented because there wasn't a safe way (that is, without using eval) to handle this use case without them.
This:
rsync "$OPT1 $SRC $TRG"
passes all your intended arguments lumped together as one argument, which rsync doesn't know how to deal with.
Try this instead:
rsync ${OPT1} ${SRC} ${TRG}
The approach suggested by #chepner didn't work on my Mac OS X (10.9.4), but eval did.
eval rsync "$OPT1 $SRC $TRG"
I am writing a simple script that rsync's a remote site to my local computer, and dynamically generates --exclude=dir flags depending on what option is specified on the command line.
#!/bin/bash -x
source="someone#somewhere.org:~/public_html/live/"
destination="wordpress/"
exclude_flags='--exclude=cache/* '
if [ "$1" == "skeleton" ] ; then
exclude_flags+='--exclude=image-files/* '
fi
rsync --archive --compress --delete $exclude_flags -e ssh $source $destination
I'm running into trouble when I try to interpolate the $exclude_flags variable on the last line. Since the variable has spaces in it, bash is automatically inserting single quotes before and after the interpolation. Here is the command which bash tried to execute (the relevant output of /bin/bash +x):
+ /usr/bin/rsync --archive --compress --delete '--exclude=cache/*' '--exclude=image-files/*' -e /usr/bin/ssh someone#somewhere.org:~/public_html/live/ wordpress/
As you can see, bash has inserted a bunch of single quotes around the individual tokens of $exclude_flags, which is causing rsync to choke.
I have tried:
What I have listed above.
Putting it in double quotes ... "$exclude_flags" .... This almost fixes the problem, but not quite. The single quotes only appear around the full content of $exclude_flags, rather than around each token.
Making $exclude_flags an array, and then interpolating it using ${exclude_flags[#]}. This gives the same output as #2.
Wrapping the whole rsync line in back-tick quotes. This gives the same output as #1.
Any ideas? This seems like a really simple and common problem in bash, so I'm sure that I'm doing something wrong, but google didn't help at all.
Thank you.
The proper way to store multiple command-line options in a variable in bash is to use an array:
source="someone#somewhere.org:~/public_html/live/"
destination="wordpress/"
options=( '--exclude=cache/*' )
if [[ "$1" == "skeleton" ]] ; then
options+=( '--exclude=image-files/*' )
fi
rsync --archive --compress --delete "${exclude_flags[#]}" -e ssh "$source" "$destination"
I am trying to save some typing with this bash script:
#!/usr/bin/env bash
n=$(($#-1))
files=${#:1:$n}
dest=${!#}
echo "$n files"
echo "${files[#]}"
echo "$dest"
rsync -av "${files[#]}" kyopti:$dest
Notice the "${files[#]}" part, I did this because it's recommended on Greg's bash tutorial. This generates an error:
rsync: link_stat "/tmp/scplot.pdf ssknplot.pdf" failed: No such file or directory (2)
But if I remove the quotes, everything works fine. I am confused, isn't this supposed to be the best practice, to add the quotes?
files is not an array. It's just a single string consisting of a space-separated list of the positional arguments. You want
files=( "${#:1:$n}" )
Then your quoted use of files in the rsync command will work as expected.