Shell Script: Concatenate string while interating

Question

I am writing a shell script that iterates over directory content and searches for pdf files and creates a string listing all pdf files in it e.g. "pdffile1.pdf pdffile2.pdf pdffile3.pdf".

pdffiles=""

#get files in pdf directory
for filename in $1/*; do
    fn=$(basename "$filename")
    #check if file exist
    if [ -f "$filename" ]; then
        #grab only pdf files
        if [ ${filename: -4} == ".pdf" ]; then
            pdffiles = $filename $pdffiles
        fi
    fi
done

The thing is this code pdffiles = $filename $pdffiles is wrong and shell script outputs following error message ./mergepdfs.sh: line 39: pdffiles: command not found. What is wrong with that line?

Why not just: pdffiles=$( cd $1 && ls *.pdf 2> /dev/null )?

William Pursell
– William Pursell

2012-02-15 12:30:57 +00:00
Commented Feb 15, 2012 at 12:30 — William Pursell
– William Pursell, Commented Feb 15, 2012 at 12:30

dimba · Accepted Answer · 2012-02-15 10:04:29Z

4

Don't use spaces around '=' when assigning:

x = 1 # execution of x with arguments '=' and '1'
x=1   # setting shell variable x

answered Feb 15, 2012 at 10:04

dimba

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Comments

user unknown · Accepted Answer · 2012-02-15 11:29:12Z

2

Why not simply:

pdffiles=$1/*.pdf

If you like to get them in array form:

pdffiles=($1/*.pdf)

Output all:

 echo ${pdffiles[*]}

Output size:

 echo ${#pdffiles[*]}

Output a single name:

 echo ${pdffiles[4]}

edited Feb 15, 2012 at 11:29

answered Feb 15, 2012 at 11:23

user unknown

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2 Comments

glenn jackman Over a year ago

To append to an array, you can use pdffiles+=("$filename")

Michael Dillon Over a year ago

Note that assignment is not a normal shell command and therefore it is not tokenized by splitting it into words at spaces and tabs. There is no = command to be called to handle this. In fact, you can prefix any command with name=val followed by at least one space. So roughly, 1) the line is tokenized on whitespace, 2) tokens are examined for an = expression. 3) if an = is there the token is evaluated and discarded. 4) if no = then the token is treated as a command and the other tokens are all arguments to that command.

user184968 · Accepted Answer · 2012-02-15 10:03:49Z

2

I think you don't need space around =. This must be a correct line:

pdffiles=$filename' '$pdffiles

answered Feb 15, 2012 at 10:03

user184968

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