Creating a Bash shell Script

bobsinclair · 11-26-2018, 01:30 PM

I am attempting to create a script to see if an argument is regular file or not so far my Script constits of the Following

#!/bin/bash

test-f 'Example' && echo Yes

If i have Echo as the File name i receive the output Yes,but if i Replace it with the name of a Directory i receive no output

nodir · 11-26-2018, 01:41 PM

Code:

help test

or "man test" will tell you more, but for now:

Code:

help test | grep -- '-d\|-f'
      -d FILE        True if file is a directory.
      -f FILE        True if file exists and is a regular file.
$

hence "echo Yes" will not be executed as test -f will return false if you point it at a directory.

teckk · 11-26-2018, 03:51 PM

Couple of examples:

Code:

read -p "Enter file/dir/pipe name :" f_name

Code:

if [ -f "$f_name" ]; then
    echo "It's a regular file"
elif [ -d "$f_name" ]; then
    echo "It's a directory"
elif [ -p "$f_name" ]; then
    echo "It's a named pipe"
fi

#Or

Code:

[ -f "$f_name" ] && echo "It's a regular file"
[ -d "$f_name" ] && echo "It's a directory"
[ -p "$f_name" ] && echo "It's a named pipe"

#Or

Code:

for i in -f -d -p; do
    if [ "$i" "$f_name" ]; then
        echo "$i"
    fi
done

BW-userx · 11-26-2018, 04:10 PM

to use test itself, check for directory presents

Code:

#!/bin/bash

if test -d /usr; then
  echo "it is "
  else
  echo "no it isn't"
  fi

your code

Code:

#!/bin/bash

test-f 'Example' && echo Yes

test always checks for true, if it is a truth then it executes, if it is not a truth errors.

both still equate to true, being the executing condition.

if true [directory] do something, else do something else.
if !true [not directory] then do something, else do something else

if directory is there do something is a truth if it is.
if the directory is not there, then that is a truth if it is not there.

Code:

test -d /usr &&  echo "it is " ||   echo "no it isn't"

[[ -d /directory ]] && echo "it is there" || echo "it is not there"

as this is a ternary operation, BASH has no true ternary operator.

this here

Code:

userx@SlackOLatern:~/Documents$ touch Example
userx@SlackOLatern:~/Documents$ test -f 'Example' && echo "yes"
yes

userx@SlackOLatern:~/Documents$ test -f 'Example' && echo "no"
no

userx@SlackOLatern:~/Documents$ test -f 'Example' && echo "whatevr you wnat me to do"
whatevr you wnat me to do

is just you telling it to say whatever you want when the condition is true.