Im trying to run a shell script but I keep getting If: expression syntax. How to I get rid of it

Question

Good afternoon, I'm trying to run my code for assignment 4 but I keep getting an expression syntax error, can you tell me why?

#!/bin/sh
if [ "$#" -ne 1 ] then
        echo "Usage: assignment4.sh <directory_name>"
        exit 1
fi
if [ ! -d "$1" ] then
        echo "$1: No such directory"
        exit 1
fi
num_dir=0
num_file=0
num_readable=0
num_writable=0
num_executable=0
for item in "$1"/* do
#Question1
        if [-d "$item" ] then
        num_dir=$((num_dir+1))
        fi
#Question 2
        elif [ -f "$item" ] then
        num_file=$((num_file+1))
        fi
#Question 3
        if [-r "$item" ] then
  num_readable=$((num_readable+1))
        fi
#Question 4
        if [ -w "$item" ] then
        num_writable=$((num_writable+1))
        fi
#Question 5
        if [ -x "$item" ] then
        num_executable=$((num_executable+1))
        fi
done
echo "Number of directories: $num_dir"
echo "Number of files: $num_file"
echo "Number of readable items: $num_readable"
echo "Number of writable items: $num_writable"
echo "Number of executable items: $num_executable"

Answer 1

When asking questions like this, you need to tell us what the code is supposed to do (we don't know what your "assignment 4" is), and what happens instead. Don't tell us there is a syntax error, show us exactly how you execute the script and the exact error message.

That said, your issues here are straightforward:

1. if statements require specific syntax: if condition; then action; fi. The ; are "list terminators" and you need a list terminator to separate the if command from the then action. The same goes for the for loops which need for thing in list_of_things; do action; done. For both of these, you can use a ; or a newline as a list terminator, but you need to have a list terminator. Either of these would be fine:

   if [ "$#" -ne 1 ]; then
      command 
   fi
   for item in "$1"/*; do
     command
   done
   

   or

   if [ "$#" -ne 1 ]
   then
     command
   fi
   for item in "$1"/*
   do
     command
   done
   

2. The [ is a command, so like all commands, it requires a space both before and after to make it clear that it is a single token. This means that if [-r "$item" ] is a syntax error, you need if [ -r "$item" ].

3. if blocks are closed by fi. However, elif and else are part of the same block, so if you close your opening if, you cannot add an elif or an else afterwards, you would need to open a new if first.

Putting all this together, this is a working version of your script, keeping the exact same logic and only correcting the syntax errors:

#!/bin/sh
if [ "$#" -ne 1 ]; then
        echo "Usage: assignment4.sh <directory_name>"
        exit 1
fi
if [ ! -d "$1" ]; then
        echo "$1: No such directory"
        exit 1
fi
num_dir=0
num_file=0
num_readable=0
num_writable=0
num_executable=0
for item in "$1"/*; do
  #Question1
  if [ -d "$item" ]; then
    num_dir=$((num_dir+1))
  #Question 2
  elif [ -f "$item" ]; then
  num_file=$((num_file+1))
  fi
  #Question 3
  if [ -r "$item" ]; then
    num_readable=$((num_readable+1))
  fi
  #Question 4
  if [ -w "$item" ]; then
    num_writable=$((num_writable+1))
  fi
  #Question 5
  if [ -x "$item" ]; then
    num_executable=$((num_executable+1))
  fi
done
echo "Number of directories: $num_dir"
echo "Number of files: $num_file"
echo "Number of readable items: $num_readable"
echo "Number of writable items: $num_writable"
echo "Number of executable items: $num_executable"