Script - issue with SED command

English Programming/Scripting
1

Hi folks,

I’m attaching an excerpt from a script I’m working at:

for i in {1..$line_nr_log}; do
    tb=$(sed "$i"'q;d '"$log"); #line i of file log.txt (cotnaining the file/dir to be backed up) is read into variable $tb
    cp -v --parents $tb $backupdir >> $temp_operations_log; #file $tb is copied to the backup directory. $tb contains the path of the file relative to /home. All directories contained in the relative path are copied in the backup directory in order to preserve the original path; output of the command obtained in verbose mode is redirected to the temp_operations_log file
done

I’m getting following errors when running bash -xv for this script:


for i in {1..$line_nr_log}; do
    tb=$(sed "$i"'q;d '"$log"); #line i of file log.txt (cotnaining the file/dir to be backed up) is read into variable $tb
    cp -v --parents $tb $backupdir >> $temp_operations_log; #file $tb is copied to the backup directory. $tb contains the path of the file relative to /home. All directories contained in the relative path are copied in the backup directory in order to preserve the original path; output of the command obtained in verbose mode is redirected to the temp_operations_log file
done
+ for i in '{1..$line_nr_log}'
sed "$i"'q;d '"$log")
sed "$i"'q;d '"$log"
++ sed '{1..2609}q;d /var/run/media/BACKUP/BACKUP/fbackup_03.05.2014/log'
sed: -e expression #1, char 3: unknown command: `.'
+ tb=
+ cp -v --parents
cp: missing file operand
Try 'cp --help' for more information.

I guess there is something wrong about the syntax of the SED command, however I can’t figure out which the issue is.

I’m getting the same errors when replacing the $(sed …) with sed ....

On the other hand when using sed without variables and only with single quotes I’m not getting any errors. Here’s an example:

central_backup_dir=`sed '1q;d' /home/test/bin/Backup_Scripts_Parameters`; #reading the path of the central backup directory, which is contained by the first line of the Backup_Scripts_Parameters file (this file contains certain parameters of the scripts fbackup.sh and dbackup.sh)

Thanks in advance for your help!

Cheers,
Liviu

2

As you can see, the $i is evaluated as {1…2609}, which I think is not what you want (and which sed (not SED btw) does not understand.

Thus IMHO you must concentrate on the

for i in {1..$line_nr_log}

to check what it does and what it should do.

3

brace expansions comes first before variable expansions. In this case it is seen as a literal $line_nr_log

for i in {1..$line_nr_log}

Use a C-style for loop instead.

for ((i=0;i<${#line_nr_log};i++))

Also “Don’t Read Lines With For”, use a while loop instead

while read -r line; do echo "$line"; done < log.txt

You might not need sed for this imo. You can paste the sample input of your file and a sample output that you desire. So the folks can see what are you really trying to do.

4

And please do not use the HTML tags, but the CODE tags. It is the # button.

5

If i understand correctly you are trying to loop over the files in a directory and run sed on each file using the for loop. If so you can use a glob instead

for i in ./*; do echo "${i#*/}"; done

If you need to do some test insert your test afer the do

for i in ./*; do  -f $i ]] && ....; done

This sed ‘1q;d’ reads the very first line of the file (if im not mistaken), if so you can test try this.

for i in ./*;do  -f "$i" ]] && read -r foo < "$i" && echo "$foo"; done

A lot of this is just a guess and it would end up in a guessing games unless you state what are you really trying to do aka EndGoal :wink:

6

If you are inside the directory of your files e.g. you have cd into it, try this and hopefully it will give you and idea.

for i in ./; do -f “$i” ]] && read -r FirstLine < “$i” && echo "First line of ${i##/} is $FirstLine"; done