Trouble with Shell Script Compressing file

ETC Homework & Coursework Questions
1

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  1. The problem statement, all variables and given/known data:
    You will create a shell script that performs the following action:
  • Use a parameter to pass a file that contains a list of file locations.
  • Read the list of file locations and store it as a variable
  • Using the list of file location create a compressed file, do not show any output from this command
  • Display the contents of the compressed file
  • Display the size of the newly created compressed file

Keep getting the following errors/outputs:
tar: Removing leading `/' from member names
tar: /phager/Desktop: Cannot stat: No such file or directory
tar: Exiting with failure status due to previous errors

The script still creates the compression file, but when I try to display the file size and file name with the stat command I get more info than I want, all I need to display is the file size and name after the echo command "The size of file1.tgz is:"

  1. Relevant commands, code, scripts, algorithms:
#!/bin/bash
echo "Creating Compressed File from file1"
while read $file1; do
echo "Contents of file are:"
cat file1
tar cvzf file1.tgz /phager/Desktop
echo "The size of file1.tgz is:"
stat file1.tgz
done < file1

  1. The attempts at a solution (include all code and scripts):

  2. Complete Name of School (University), City (State), Country, Name of Professor, and Course Number (Link to Course):
    Leeward Community College, Pearl City, HI, USA, Peter Gross, ICS240, ICS 240 Operating Systems • Section 0

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2

You seem to be confused about how you reference parameters passed to a shell script, about how the variable name passed to and filled in by the shell's read built-n works, and about how to reference variables created in your shell script.

I would suggest re-reading the manual page for bash on your system (using the command: man bash ) paying special attention to the discussion in the PARAMETERS section, in the EXPANSION section, and the description of the read utility in the SHELL BUILTIN COMMANDS section.

If you have a file named list_of_files containing:

file1
file2
file3

and the script:

#!/bin/bash
listfile="$1"
while read file
do	echo "Read filename $file from $listfile."
done < "$listfile"

in a file named readlist which you have made executable with the command:

chmod +x readlist

then see what happens when you run the command:

./readlist list_of_files

Does this help?

3

The first tar line is invormative. The rest should be self- explaining, no?

That will be an empty file - not empty, but just binary zeroes. How about man stat ?

4 
Keep getting the following errors/outputs:
tar: Removing leading `/' from member names

tar does it for your own protection. To uncompress, specify -C.

The script still creates the compression file, but when I try to display the file size and file name with the stat command I get more info than I want, all I need to display is the file size and name after the echo command "The size of file1.tgz is:"

du -h $file, will suffice I guess

5

can be understood as redirecting any 'error message' to /dev/zero.
Like:

tar cvzf "$file1.tgz" "$file1" 2>/dev/zero

Alternativly, you could redirect and appending (the double >> ) to a logfile like:

tar cvzf "$file1.tgz" "$file1" 2>>"./$file_list.log"

hth

6

Although /dev/zero can be used this way on most systems, the conventional device for dumping output into the trash can is /dev/null which is described by the standards as:

/dev/null  An empty data source and infinite data sink. Data written to /dev/null shall be
           discarded. Reads from /dev/null shall always return end-of-file (EOF).

The standards do not require systems to provide /dev/zero .

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