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The runtime arguments are as follows: $1 is the path to the file containing the list of files $2 is the path to the directory containing the files What I want to do is check that each file listed in $1 exists in the $2 directory

I'm thinking something like:

for f in 'cat $1'
do
if (FILEEXISTSIN$2DIRECTORY)
then echo '$f exists in $2'
else echo '$f is missing in $2' sleep 5 exit
fi
done

As you can see, I want it so that if any of the files listed in $1 don't exist in the directory $2, the script states this then closes. The only part I can't get my head around is the (FILEEXISTSIN$2DIRECTORY) part. I know that you can do [ -e $f ] but I don't know how you can make sure its checking that it exists in the $2 directory. Thank you, I hope you can help this bash noob out.

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2 Answers

up vote 2 down vote accepted

The best way to iterate over the lines in a file is using the read builtin in a while loop. This is what you are looking for:

while IFS= read -r f; do
    if [[ -e $2/$f ]]; then
        printf '%s exists in %s\n' "$f" "$2"
    else
        printf '%s is missing in %s\n' "$f" "$2"
        exit 1
    fi
done < "$1"
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Thank you, I haven't really used while loops or the read function yet, so I will play around with this. –  user29772 Jan 5 '13 at 17:16
    
@user29772 mywiki.wooledge.org/BashFAQ/001 –  jordanm Jan 5 '13 at 17:16
    
Is the IFS= part necessary if the files in the list are just separated by white space (the file names contain no spaces :) ) –  user29772 Jan 5 '13 at 17:46
    
Putting it in a more sensible way, omitting IFS= is only necessary when you want leading and trailing blanks to be stripped from the beginning and end of the lines being read. It makes no sense to omit it otherwise. –  Stephane Chazelas Jan 5 '13 at 18:04
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The shell way, you'd write it:

comm -23 <(sort -u < "$1") <(ls -- "$2")

(assuming a shell with support for process substitution like ksh, zsh or bash)

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