I haven't found anything to deal with this particular situation. Maybe there is a easy way that I'm overlooking instead of checking for a string to catch this scenario. When I check an input for existence of a file, if the input is ~/filecheck , this won't work. I get negative results while the file is in my home folder. Any suggestions for improvement to any part of the script I will definitely appreciate. I also have to use an input instead of a argument. Thanks for any help.
my test script
read -p "Enter: " input
echo $input
if [ -f $input ]; then
read -p "Do you REALLY want to delete this file?:" input2
if [[ $input2='y' || $input2 = 'Y' ]]
then
rm -f $input
elif [[ $input2='n' || $input2='N' ]]
then
exit
else
echo "Invaild Option"
exit
fi
else
echo Invaild Option!
exit
fi
Since you are entering input string as ~/filecheck shell doesn't expand tilde while using condition with -f in [ -f $input ]
You can use it this way but it is not recommended and potentially dangerous as arbitrary commands can be run by user:
if [[ -f $(bash -c "echo $input") ]]; then
echo "file exists"
fi
EDIT: As per the comments below to avoid risky bash -c you can use:
if [[ -f "${input/\~/$HOME}" ]]; then
echo "file exists"
fi
You can't have tilde expansion in this part of the program without using something based on eval—and you don't want to do that with user input. So, your poor-man solution will be to substitute any potential leading ~/ with the expansion of $HOME/. Here's the adaptation of your script in an arguably better style:
#!/bin/bash
read -e -p "Enter: " input
input=${input/#~\//$HOME/} # <--- this is the main idea of this answer (and it's rather poor)
echo "$input"
if [[ -f $input ]]; then
read -e -p "Do you REALLY want to delete this file? " input2
if [[ ${input2,,} = y ]]; then
rm -f -- "$input"
elif [[ ${input2,,} = n ]]; then
exit
else
echo "Invalid Option"
exit
fi
else
echo "Invalid Option!"
fi
exit
Now, out of curiosity, why are you spending time to make a wrapper around rm? you're making a clunky interface to an already existing program, without adding anything to it, only rendering it less powerful and less easy to use.
If all what you want it's to ask the user before deleting, you can use:
rm -i
This will give you appropriate error in the case file does not exist.
Related
I'm trying to write a script that will only accept exactly one argument. I'm still learning so I don't understand what's wrong with my code. I don't understand why, even though I change the number of inputs the code just exits. (Note: I'm going to use $dir for later if then statements but I haven't included it.)
#!/bin/bash
echo -n "Specify the name of the directory"
read dir
if [ $# -ne 1 ]; then
echo "Script requires one and only one argument"
exit
fi
You can use https://www.shellcheck.net/ to double check your syntax.
$# tells you how many arguments the script was called with.
Here you have two options.
Option 1: Use arguments
#!/bin/bash
if [[ $# -ne 1 ]]
then
echo "Script requires one and only one argument"
exit 1
else
echo "ok, arg1 is $1"
fi
To call the script do: ./script.bash argument
Use [[ ]] for testing conditions (http://mywiki.wooledge.org/BashFAQ/031)
exit 1: by default when a script exists with a 0 status code, it means it worked ok. Here since it is an error, specify a non-zero value.
Option 2: Do not use arguments, ask the user for a value.
Note: this version does not use arguments at all.
#!/bin/bash
read -r -p "Specify the name of the directory: " dir
if [[ ! -d "$dir" ]]
then
echo "Error, directory $dir does not exist."
exit 1
else
echo "ok, directory $dir exists."
fi
To call the script do: ./script.bash without any arguments.
You should research bash tutorials to learn how to use arguments.
Is there a way to check the user's response to a rm -i execution?
I'd like to echo something depending on whether or not the user responded with y or n.
The command returns successfully regardless of the user's response, so this attempt did not work:
$ rm -i testfile.txt && echo "The file was deleted."
remove testfile.txt? n
The file was deleted.
My reasoning was that the echo part would only be executed if the rm part was successful, but obviously a n response also counts as successful execution.
I would also like to be able to vary the message depending on the answer. This code would do it, but it's not very pretty.
file=testfile.txt
touch $file
read -p "Are you sure (y/n)? " answer
if [[ $answer =~ ^[yY](es|ES)?$ ]]; then
rm $file
echo "Deleted file."
else
echo "Did nothing."
fi
Surely there must be a way to get the input to rm -i.
How?
You can check, if the file was actually deleted. Eg.
rm -i testfile.txt && [[ ! -e testfile.txt ]] && echo "The file was deleted."
If the rm is successful, then test, if the file does not exist [[ ! -e file ]] and only then display the message. It covers the case, when you try to remove the file that does not exist, since then the rm will return with the exit code different than 0.
In case you want to display messages for when the file was purposefully deleted or not deleted, plus extra info on error, then you can extend the previous code like so:
rm -i testfile.txt && {
[[ ! -e testfile.txt ]] && echo "The file was deleted." || echo "Ignored"
} || echo "Error"
Most of the problem with your attempt is that you are trying to accommodate too many possible inputs, or paradoxically limiting the input to specifically "yes" or "no" while excluding "yeah", "yup", "nope", etc. A simply y or n will do (in fact, the only distinction you need to make is between y and not-y).
read -p "Are you sure (y/n)? " answer
if [[ $answer = [yY]* ]]; then
rm -- "$file"
echo "Deleted file."
else
echo "Did nothing."
fi
If you like, you can use shopt -s nocasematch before the if statement so that you can simply write if [[ $answer = y* ]]; then to ignore the case of the user's actual input.
Your original question would require some hook provided by rm itself, which it does not do.
I've got a script that I'm reading the input from users. Here's my code:
if [ -z $volreadexists ]; then
echo -e "\tThis will overwrite the entire volume (/dev/vg01/$myhost)...are you sure?"
read REPLY
echo
if [[ $REPLY =~ ^[Yy]$ ]]; then
echo -e "\t\tContinuing"
syncvolume
else
echo "Fine...skipping"
fi
fi
I'm having to use read REPLY because read by itself doesn't insert tabs. What I'm looking for is something similar to:
read -p "\tDoes this look OK? (n for No)" -n 1 -r
Where \t would tab over the read prompt.
How can I add tabs to a read prompt?
UPDATE: Thanks for the great answer from #gniourf!:
read -p $'\tDoes this look OK? (n for No)' -n 1 -r
However, I found an issue. When I attempt to use a variable there it doesn't translate it:
read -p $'\tThis will overwrite the entire volume (/dev/vg01/$myhost)...are you sure? ' -n 1 -r
becomes
This will overwrite the entire volume (/dev/vg01/$myhost)...are you sure?
where I want:
This will overwrite the entire volume (/dev/vg01/server1)...are you sure?
Using doublequotes doesn't work either :(
Any ideas?
Just use ANSI-C quoting:
read -p $'\tDoes this look OK? (n for No)' -n 1 -r
Now, if you want to use variable expansions too, you can mix different quotes like so:
read -p $'\t'"This will overwrite the entire volume (/dev/vg01/$myhost)...are you sure? " -n 1 -r
Here I only used ANSI-C quoting for the tab character. Make sure you don't leave any spaces between $'\t' and "This will....".
I ended up referencing this answer:
Read a variable in bash with a default value
and created a workaround. It's not perfect, but it works:
myhost="server1"
if [ -z $volreadexists ]; then
read -e -i "$myhost" -p $'\tJust checking if it\'s OK to overwrite volume at /dev/vg01/'
echo
if [[ $REPLY =~ ^$myhost[Yy]$ ]]; then
echo -e "\t\tContinuing"
else
echo "Fine...skipping"
fi
fi
I'm trying to compile a script that will read user input, and check if the file after the y/n statement. Then it will make files executable. I think the problem with my script is conditional ordering but check it out yourself:
target=/home/user/bin/
cd $target
read -p "This will make the command executable. Are you sure? (y/n)" CONT
if [ "$CONT" == "y" ];
then
chmod +x $1
echo "File $1 is now executable."
else
if [ "$(ls -A /home/user/bin/)" ];
then
echo "File not found."
else
echo "Terminating..."
fi
fi
As I said, I need the script to scan for the file after the y/n statement is printed. The script works fine how it is but still gives the "file is now executable" even if the argument file doesn't exist (but just gives the standard system "cannot find file" message after the echo'd text).
Your script is mostly correct, you just need to check if the file exists first. Also, it's not the best practice to use cd in shell scripts and not needed here.
So re-writing it
#!/bin/bash
target="/home/user/bin/$1"
if [[ ! -f $target ]]; then
echo "File not found."
else
read -p "This will make the command executable. Are you sure? (y/n) " CONT
if [[ $CONT == "y" ]]; then
chmod +x "$target"
echo "File $1 is now executable."
else
echo "Terminating..."
fi
fi
To get an understanding:
Your script will take one argument (a name of a file).
You ask if you want to make that file executable.
If the answer is 'yes', you make the file executable.
Otherwise, you don't.
You want to verify that the file exists too?
I'm trying to understand your logic. What does this:
if [ "$(ls -A /home/user/bin/)" ];
suppose to do. The [ ... ] syntax is a test. And, it has to be one of the valid tests you see here. For example, There's a test:
-e file: True if file exists.
That mean, I can see if your file is under /home/user/bin:
target="/home/user/bin"
if [ -e "$target/$file" ] # The "-e" test for existence
then
echo "Hey! $file exists in the $target directory. I can make it executable."
else
echo "Sorry, $file is not in the $target directory. Can't touch it."
fi
Your $(ls -A /home/user/bin/) will produce a file listing. It's not a valid test like -e unless it just so happens that the first file in your listing is something like -e or -d.
Try to clarify what you want to do. I think this is something more along the lines you want:
#! /bin/bash
target="/home/user/bin"
if [ -z "$1" ] # Did the user give you a parameter
then
echo "No file name given"
exit 2
fi
# File given, see if it exists in $target directory
if [ ! -e "$target/$1" ]
then
echo "File '$target/$1' does not exist."
exit 2
fi
# File was given and exists in the $target directory
read -p"Do you want $target/$1 to be executable? (y/n)" continue
if [ "y" = "$continue" ]
then
chmod +x "$target/$1"
fi
Note how I'm using the testing, and if the testing fails, I simply exit the program. This way, I don't have to keep embedding if/then statements in if/then statements.
I'm writing a reasonably lengthy script (or what I would consider lengthy - you could probably do it in a few hours). I basically have a file (named .restore.info) which contains files of names. In part of the script, I want to test "If cannot find filename in .restore.info, then says “Error: restored file does not exist”. Apologies if this doesn't make sense for you guys (for me, it does in the grand scheme of things). So if type this in the command line:
sh MYSCRIPT filename
It will search for the string filename in the .restore.info file, and if it cant find anything, it should produce an error message.
Basically, I need the top line of this coded translated into a UNIX bash statement and something that actually makes sense!:
If grep $1 .restore.info returns an exist status of 1; then
echo “Filename does not exist!”
fi
Thanks in advance! Please ask me if you need me to clarify anything more clearly as I know I'm not the best explainer, and I'll get back to you in less than a minute! (+rep and best answer of course will be given!)
You probably only care if grep exits with a non-zero exit status:
if ! grep -q "$1" .restore.info; then
echo "Filename does not exist!"
fi
but if you really do care about a specific exit status (1, in this case):
if ! grep -q "$1" .restore.info && [[ $? -eq 1 ]]; then
echo "Filename does not exist!"
fi
Use grep -q
grep -q "filename" .restore.info && echo "found match"
or
! grep -q "filename" .restore.info && echo "not found"
grep -l 'filename' .restore.info
if [ $? = 0 ];then
echo "found it"
else
echo "not found"
fi