The shell not redirecting output of tar to file

Question

I am assuming this is a simple issue, but I don't have any one to double check my work.

Here's my bash script

#!/bin/bash

# establish date format and dump name
DATE=$(date +"%Y%m%d-%H%M")
DUMPFILE=$DATE.dump

# path to log dir and name of output log file 
LOGDIR=/opt/mongodb/backups/logs
DBLOG=$DATE-dump.log

# backup the database and output to a dump file, redirect output to a log
docker exec -i mongodb sh -c "mongodump --archive" > \
    $DUMPFILE 2> \ 
    $LOGDIR/$DBLOG

# archive the dump file and the file uploads
ARCHIVENAME=$DATE.tgz
ARCHIVELOG=$DATE-archive.log

tar -czvf $ARCHIVENAME /opt/mongodb/$DUMPFILE /opt/mongodb/files &> \
    $LOGDIR/$ARCHIVELOG

Where I'm stuck, the script correctly outputs the dump log. However when it gets to the end I receive

./backup.sh: line 20: /opt/mongodb/backups/logs/20250328-0942-archive.log: No such file or directory

I've attempted using the absolute path instead of the of the var:

tar -czvf $ARCHIVENAME /opt/mongodb/$DUMPFILE /opt/mongodb/files &> \
    /opt/mongodb/backups/logs/$ARCHIVENAME

But I get the same error. I'm assuming this is either my bad understanding of redirects, tar, or a syntax error. Any help would be appreciated.

EDIT: A file called "' '" gets created each time I run the script. If run

cat ' '

I see that file is the log, so it's does redirect the output to a file, just not in the desired manner.

Answer 1

You most likely have one or several space characters at the end of the last line that is supposed have a backslash character at the end.

A line that is continued on the next line by a backslash must not have anything after the backslash, not even a space.

Since you have space after the backslash, the space is quoted, so you are, in effect, saying

some-command &> ' '

The next line after that tries to run the non-existing logfile as a command. This is what generates the “No such file or directory” error message.

---

My take on your script, with my personal preferences baked into it, and also taking into account what Paul_Pedant says in the comments about quoting and line breaks.

#!/bin/bash

# Move to the MongoDB directory.  Terminate if it fails.
cd /opt/mongodb || exit

log_dir=backups/logs
mkdir -p "$log_dir" || exit

printf -v now '%(%Y%m%d-%H%M)T' -1

# Dump file and dump log file.
dump_file=$now.dump
dump_log=$log_dir/$dump_file.log

# Archive file and archive log file.
archive_file=$now.tgz
archive_log=$log_dir/$archive_file.log

# Dump the MongoDB database to a file.
docker exec -i mongodb \
        sh -c 'mongodump --archive' >"$dump_file" 2>"$dump_log"
err=$?

# Archive the dump and the files with full path.
tar -v -cz -f "$archive_file" \
        "$PWD/$dump_file" "$PWD"/files 2>"$archive_log"

if (( err || $? )); then
        echo 'There were errors in dumping or archiving'
        printf 'See "%s" and "%s"\n' "$dump_log" "$archive_log"
fi >&2

Answer 2

I'm guessing you or your editor put a space after the \ on the line, causing it to redirect to \ (' ') instead of to the file.