Test multiple file conditions in one swoop (BASH)?

Question

Often when writing for the bash shell, one needs to test if a file (or Directory) exists (or doesn't exist) and take appropriate action. Most common amongst these test are...

-e - file exists, -f - file is a regular file (not a directory or device file), -s - file is not zero size, -d - file is a directory, -r - file has read permission, -w - file has write, or -x execute permission (for the user running the test)

This is easily confirmed as demonstrated on this user-writable directory....

#/bin/bash

if [ -f "/Library/Application Support" ]; then
echo 'YES SIR -f is fine'
else echo 'no -f for you'
fi

if [ -w "/Library/Application Support" ]; then
echo 'YES SIR -w is fine'
else echo 'no -w for you'
fi

if [ -d "/Library/Application Support" ]; then
echo 'YES SIR -d is fine'
else echo 'no -d for you'
fi

➝ no -f for you ✓
➝ YES SIR -w is fine ✓
➝ YES SIR -d is fine ✓

My question, although seemingly obvious, and unlikely to be impossible - is how to simply combine these tests, without having to perform them separately for each condition... Unfortunately...

if [ -wd "/Library/Application Support" ]  
  ▶  -wd: unary operator expected

if [ -w | -d "/Library/Application Support" ]   
  ▶  [: missing `]'
  ▶  -d: command not found

if [ -w [ -d "/Library.... ]]   &  if [ -w && -d "/Library.... ] 
  ▶  [: missing `]'

➝ no -wd for you ✖
➝ no -w | -d for you ✖
➝ no [ -w [ -d .. ]] for you ✖
➝ no -w && -d for you ✖

What am I missing here?

Answer 1

You can use logical operators to multiple conditions, e.g. -a for AND:

MYFILE=/tmp/data.bin
if [ -f "$MYFILE"  -a  -r "$MYFILE"  -a  -w "$MYFILE" ]; then
    #do stuff
fi
unset MYFILE

Answer 2

Of course, you need to use AND somehow as Kerrek(+1) and Ben(+1) pointed it out. You can do in in few different ways. Here is an ala-microbenchmark results for few methods:

Most portable and readable way:

$ time for i in $(seq 100000); do [ 1 = 1 ] && [ 2 = 2 ] && [ 3 = 3 ]; done
real    0m2.583s

still portable, less readable, faster:

$ time for i in $(seq 100000); do [ 1 = 1 -a 2 = 2 -a 3 = 3 ]; done
real    0m1.681s

bashism, but readable and faster

$ time for i in $(seq 100000); do [[ 1 = 1 ]] && [[ 2 = 2 ]] && [[ 3 = 3 ]]; done
real    0m1.285s

bashism, but quite readable, and fastest.

$ time for i in $(seq 100000); do [[ 1 = 1 && 2 = 2 && 3 = 3 ]]; done
real    0m0.934s

Note, that in bash, "[" is a builtin, so bash is using internal command not a symlink to /usr/bin/test exacutable. The "[[" is a bash keyword. So the slowest possible way will be:

time for i in $(seq 100000); do /usr/bin/\[ 1 = 1 ] && /usr/bin/\[ 2 = 2 ] && /usr/bin/\[ 3 = 3 ]; done
real    14m8.678s

Answer 3

You want -a as in -f foo -a -d foo (actually that test would be false, but you get the idea).

You were close with & you just needed && as in [ -f foo ] && [ -d foo ] although that runs multiple commands rather than one.

Here is a manual page for test which is the command that [ is a link to. Modern implementations of test have a lot more features (along with the shell-builtin version [[ which is documented in your shell's manpage).

Answer 4

check-file(){
    while [[ ${#} -gt 0 ]]; do
        case $1 in
           fxrsw) [[ -f "$2" && -x "$2" && -r "$2" && -s "$2" && -w "$2" ]] || return 1 ;;
            fxrs) [[ -f "$2" && -x "$2" && -r "$2" && -s "$2" ]] || return 1 ;;
             fxr) [[ -f "$2" && -x "$2" && -r "$2" ]] || return 1 ;;
              fr) [[ -f "$2" && -r "$2" ]] || return 1 ;;
              fx) [[ -f "$2" && -x "$2" ]] || return 1 ;;
              fe) [[ -f "$2" && -e "$2" ]] || return 1 ;;
              hf) [[ -h "$2" && -f "$2" ]] || return 1 ;;
               *) [[ -e "$1" ]] || return 1 ;;
        esac
        shift
    done
}

check-file fxr "/path/file" && echo "is valid"

check-file hf "/path/folder/symlink" || { echo "Fatal error cant validate symlink"; exit 1; }

check-file fe "file.txt" || touch "file.txt" && ln -s "${HOME}/file.txt" "/docs/file.txt" && check-file hf "/docs/file.txt" || exit 1

if check-file fxrsw "${HOME}"; then
    echo "Your home is your home from the looks of it."
else
    echo "You infected your own home."
fi