1

I have written a script for the purpose of calling it from other scripts and am having issues doing so.

The script I wish to call from other scripts works correctly:

#!/bin/bash

####################################################################################################
# This script will compare two directories given as args.
#
# exit status: 0 --> if directories are the same
#              1 --> if directories are not the same
#              2 --> incorrect number of args
#              3 --> one or more of the directories does not have read permissions
#              4 --> one or more of the directories does not exists
#              5 --> one or more of the directories is not a directory
####################################################################################################


[ $# -ne 2 ] && exit 2

[ ! -r "$1" ] || [ ! -r "$2" ] && exit 3
[ ! -e "$1" ] || [ ! -e "$2" ] && exit 4
[ ! -d "$1" ] || [ ! -d "$2" ] && exit 5

dir_1="$1"
dir_2="$2"
sha1_dir_1=$(find "$dir_1" -type f \( -exec sha1sum {} \; \) | awk '{print $1}' | sort | sha1sum)
sha1_dir_2=$(find "$dir_2" -type f \( -exec sha1sum {} \; \) | awk '{print $1}' | sort | sha1sum)

[ "$sha1_dir_1" = "$sha1_dir_2" ] && exit 0
[ "$sha1_dir_1" != "$sha1_dir_2" ] && exit 1

I have tested it by calling it from the command line. Below is a test script which I cannot seem to call the above script from successfully:

#!/bin/bash

dir_1="~/test"
dir_2="~/test1"
directories_are_same="$(~/bin/compare_directories "$dir_1" "$dir_2")"

{
    if [ $directories_are_same -eq 3 ]; then
        echo "One of the directories $dir_1 and $dir_2 does not have read permissions!"
        exit 1
    elif [ $directories_are_same -eq 4 ]; then 
        echo "One of the directories $dir_1 and $dir_2 does not exist!"
        exit 1
    elif [ $directories_are_same -eq 5 ]; then
        echo "One of the directories $dir_1 and $dir_2 is not a directory!"
        exit 1
    fi
} >&2

if [ $directories_are_same -eq 0 ]; then
    echo "The directories $dir_1 and $dir_2 contain identical content"
    exit 0
elif [ $directories_are_same -eq 1 ]; then
    echo "The directories $dir_1 and $dir_2 do not contain identical content"
    exit 0
else
    echo "Something went wrong" >&2
    exit 1
fi

The output from the test script I am getting is:

/home/astral/bin/updates_dir_if: line 8: [: -eq: unary operator expected
/home/astral/bin/updates_dir_if: line 11: [: -eq: unary operator expected
/home/astral/bin/updates_dir_if: line 14: [: -eq: unary operator expected
/home/astral/bin/updates_dir_if: line 20: [: -eq: unary operator expected
/home/astral/bin/updates_dir_if: line 23: [: -eq: unary operator expected
Something went wrong

I have tried using the full path to the script, the relative path from the test script which would be ./, and the way that it currently is ~/bin/scriptname. All give the same results.

I have read some posts which seem to imply that what I am doing should work, such as:

StackOverflow post

Quote your args in Testscript 1:

echo "TestScript1 Arguments:"
echo "$1"
echo "$2"
echo "$#"
./testscript2 "$1" "$2"

What am I doing incorrectly?

Improve this question
13
  • 1
    Run your calling script with bash -x yourscript Commented Feb 24, 2021 at 15:41
  • 1
    Related question regarding function output vs. exit status: Returning value from called function in a shell script Commented Feb 24, 2021 at 15:56
  • 1
    @AstralAxiom : That a script runs fine from the command line, does not mean it runs well from another context. Scripts can be sensitive to environment, working directory and so on. In addition, a possible bug is that you did not quote $directories_are_same. While it may work if everything goes well, it really depends on the correct output of compare_directories in your case, and quoting it would mean one thing less which you have to worry. Commented Feb 25, 2021 at 8:41
  • 1
    I don't understand why you are catching the stdout of compare_directories. Actually, the result of the comparision is communicated to the caller via the exit code, not stdout. Commented Feb 26, 2021 at 8:02
  • 1
    @AstralAxiom : I now see that you reflected this in your own answer already. In this case, the quotes around $? and $directories_are_same are of course unnecessary, but they don't harm. Commented Feb 26, 2021 at 8:11

1 Answer 1

Reset to default
1

I figured it out. The exit status is what I need, so I need to call it and set the variable to the exit status stored in $?. The issue is that I was catching the stdout of the other script and storing it in the variable directories_are_same as if it were a return value that I was expecting, when what I needed was its exit status. I could echo something from the other script and then treat the stdout as a returned string, but that is not how this script was designed.

Here is the working test script:

#!/bin/bash

dir_1=~/test
dir_2=~/test1
~/bin/compare_directories "$dir_1" "$dir_2"
directories_are_same="$?"

{
    if [ "$directories_are_same" -eq 3 ]; then
        echo "One of the directories $dir_1 and $dir_2 does not have read permissions!"
        exit 1
    elif [ "$directories_are_same" -eq 4 ]; then 
        echo "One of the directories $dir_1 and $dir_2 does not exist!"
        exit 1
    elif [ "$directories_are_same" -eq 5 ]; then
        echo "One of the directories $dir_1 and $dir_2 is not a directory!"
        exit 1
    fi
} >&2

if [ "$directories_are_same" -eq 0 ]; then
    echo "The directories $dir_1 and $dir_2 contain identical content"
    exit 0
elif [ "$directories_are_same" -eq 1 ]; then
    echo "The directories $dir_1 and $dir_2 do not contain identical content"
    exit 0
else
    echo "Something went wrong" >&2
    exit 1
fi

Now when the directories are different I get:

The directories /home/astral/test and /home/astral/test1 do not contain identical content

and when they are the same I get:

The directories /home/astral/test and /home/astral/test1 contain identical content
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4 Comments

A full path path is probably not required. "~/test" does not work because you quoted it and bash interprets the quoted ~ literally (meaning, this isn't your home directory but a directory named literally ~). dir_1=~/test should work too (note the missing quotes).
Instead of updating your answer by appending new information, you should re-write it as if you knew everything already – the history is preserved in the edit history.
OK, thanks! I did not want to take the credit when I was not the one who noticed that : )
@AstralAxiom : Bash is not a programming language, it is a scripting language. A scripting language is a programming language. At least bash is Turing complete

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