I am very new to anything terminal/linux related. I need to create a shell function that checks if a file exits (multiple files). Needs to include if/else, do/while, and for.
This is what I have but I am super lost
#!/bin/bash
for FILE in "$#"
do
if [ -f $FILE ];
then
echo "'$FILE' exists"
else
echo "'$FILE' does not exist."
break
fi
done
Related
Good Morning,
I am trying to write a korn shell script to look inside a directory that contains loads of files and check that each file also exists with .orig on the end.
For example if a file inside the directory is called 'mercury_1' there must also be a file called 'mercury_1.orig'
If there isn't, it needs to move the mercury_1 file to another location. However if the .orig file exists do nothing and move onto the next file.
I am sure it is really simple but I am not that experienced in writing Linux scripts and help would be greatly appreciated!!
Here's a small ksh snippet to check if a file exists in the current directory
fname=mercury_1
if [ -f $fname ]
then
echo "file exists"
else
echo "file doesn't exit"
fi
Edit:
The updated script that does the said functionality
#/usr/bin/ksh
if [ ! $# -eq 1 ]
then
echo "provide dir"
exit
fi
dir=$1
cd $dir
#process file names not ending with orig
for fname in `ls | grep -v ".orig$"`
do
echo processing file $fname
if [ -d $fname ] #skip directory
then
continue
fi
if [ -f "$fname.orig" ] #if equiv. orig file present
then
echo "file exist"
continue
else
echo "moving"
mv $fname /tmp
fi
done
Hope its of help!
You can use the below script
script.sh :
#!/bin/sh
if [ ! $# -eq 2 ]; then
echo "error";
exit;
fi
for File in $1/*
do
Tfile=${File%%.*}
if [ ! -f $Tfile.orig ]; then
echo "$File"
mv $File $2/
fi
done
Usage:
./script.sh <search directory> <destination dir if file not present>
Here, for each file with extension stripped check if "*.orig" is present, if not then move file to different directory, else do nothing.
Extension is stripped because you don't want to repeat the same steps for *.orig files.
I tested this on OSX (basically mv should not differ to much from linux). My test directory is zbar and destination is /tmp directory
#!/bin/bash
FILES=zbar
cd $FILES
array=$(ls -p |grep -v "/") # we search for file without extension so put them in array and ignore directory
echo $array
for f in $array #loop in array and find .orig file
do
#echo $f
if [ -e "$f.orig" ]
then
echo "found $f.orig"
else
mv -f "$f" "/tmp"
fi
done
I need to make a bash script that checks if the file or directory exists,then if the file does,it checks the executable permission.I need to modify the script to be able to give a file executable permissions from an argument.
Example: Console input ./exist.sh +x file_name should make the file executable.
This is the unfinished code that checks if the file/directory exists and if the file is executable or not. I need to add the chmod argument part.
#!/bin/bash
file=$1
if [ -x $file ]; then
echo "The file '$file' exists and it is exxecutable"
else
echo "The file '$file' is not executable (or does not exist)"
fi
if [ -d $file ]; then
echo "There is a directory named '$file'"
else
echo "There is no directory named '$file'"
fi
If you have optional arguments to your script, you need to check for them first.
In the case of just a couple of simple arguments, it would be simpler to check for them explicitly.
MAKEEXECUTABLE=0
while [ "${1:0:1}" = "+" ]; do
case $1 in
"+x")
MAKEEXECUTABLE=1
shift
;;
*)
echo "Unknown option '$1'"
exit
esac
done
file=$1
Then after you have determined that the file is not executable
if [ $MAKEEXECUTABLE -eq 1 ]; then
chmod +x $file
fi
Should you decide to add more complex options, you may want to use something like getops:example of how to use getopts in bash
Add chmod something like:
if [ ! -x "$file" ]; then
chmod +x $file
fi
This means if file does not have execute persmission, then add execute permission for the user.
So I'm trying to get into an if statement in a bash shell script but I think I'm doing something wrong, anyways here's my sample code.
#!/bin/bash
read sd
if [ -d "~/tmp/$sd" ]; then
echo "That directory exists"
else
echo "That directory doesn't exists"
fi
;;
Am I pointing it to the correct directory? I want the user to input something which will be put into "sd" and if that subdirectory exists then it'll say it does, if not then it will go to the else and say it doesn't exist.
Try:
if [ -d ~/tmp/"$sd" ]; then
or:
if [ -d "$HOME/tmp/$sd" ]; then
Quoting prevents expansion of ~ into your home directory.
Try this:-
#!/bin/bash
read sd
if [ -d ~/tmp/"$sd" ]; then
echo "That directory exists"
else
echo "That directory doesn't exists"
fi
I have to write a shell script and i don't know how to go about it.
Basically i have to write a script where i'd find a file ( it could be possibly named differently). If either file exists then it must be executed, if it returns a 0 ( no error), it should continue the build, if it's not equal to 0 ( returns with error), it should exit. If either file is not found it should continue the build.
the file i have to find could be either file.1 or file.2 so it could be either named (file.1), or (file.2).
some of the conditions to make it more clear.
1) if either file exists , it should execute - if it has any errors it should exit, if no errors it should continue.
2) none could exist, if that's the case then it should continue the build.
3) both files will not be present at the same time ( additional info)
I have tried to write a script but i doubt it's even closer to what i am looking for.
if [-f /home/(file.1) or (file.2)]
then
-exec /home/(file.1) or (file.2)
if [ $! -eq 0]; then
echo "no errors continuing build"
fi
else
if [ $! -ne 0] ; then
exit ;
fi
else
echo "/home/(file.1) or (file.2) not found, continuing build"
fi
any help is much appreciated.
Thanks in advance
DOIT=""
for f in file1.sh file2.sh; do
if [ -x /home/$f ]; then DOIT="/home/$f"; break; fi
done
if [ -z "$DOIT" ]; then echo "Files not found, continuing build"; fi
if [ -n "$DOIT" ]; then $DOIT && echo "No Errors" || exit 1; fi
For those confused about my syntax, try running this:
true && echo "is true" || echo "is false"
false && echo "is true" || echo "is false"
Just putting the line
file.sh
in your script should work, if you set up your script to exit on errors.
For example, if your script was
#!/bin/bash -e
echo one
./file.sh
echo two
Then if file.sh exists and is executable it would run and your whole script would run. If not, the script would fail when it tried to execute the non-existing file.
If you want to execute one file or the other, extend the idea to the following:
#!/bin/bash -e
echo one
./file1.sh || ./file2.sh
echo two
This means if file1.sh does not exist, it will try file2.sh and if that is there it will run and your whole script will run.
This give preference to file1 of course, meaning if they both exist, then only file1 will run.
I have a bash program that will write to an output file. This file may or may not exist, but the script must check permissions and fail early. I can't find an elegant way to make this happen. Here's what I have tried.
set +e
touch $file
set -e
if [ $? -ne 0 ]; then exit;fi
I keep set -e on for this script so it fails if there is ever an error on any line. Is there an easier way to do the above script?
Why complicate things?
file=exists_and_writeable
if [ ! -e "$file" ] ; then
touch "$file"
fi
if [ ! -w "$file" ] ; then
echo cannot write to $file
exit 1
fi
Or, more concisely,
( [ -e "$file" ] || touch "$file" ) && [ ! -w "$file" ] && echo cannot write to $file && exit 1
Rather than check $? on a different line, check the return value immediately like this:
touch file || exit
As long as your umask doesn't restrict the write bit from being set, you can just rely on the return value of touch
You can use -w to check if a file is writable (search for it in the bash man page).
if [[ ! -w $file ]]; then exit; fi
Why must the script fail early? By separating the writable test and the file open() you introduce a race condition. Instead, why not try to open (truncate/append) the file for writing, and deal with the error if it occurs? Something like:
$ echo foo > output.txt
$ if [ $? -ne 0 ]; then die("Couldn't echo foo")
As others mention, the "noclobber" option might be useful if you want to avoid overwriting existing files.
Open the file for writing. In the shell, this is done with an output redirection. You can redirect the shell's standard output by putting the redirection on the exec built-in with no argument.
set -e
exec >shell.out # exit if shell.out can't be opened
echo "This will appear in shell.out"
Make sure you haven't set the noclobber option (which is useful interactively but often unusable in scripts). Use > if you want to truncate the file if it exists, and >> if you want to append instead.
If you only want to test permissions, you can run : >foo.out to create the file (or truncate it if it exists).
If you only want some commands to write to the file, open it on some other descriptor, then redirect as needed.
set -e
exec 3>foo.out
echo "This will appear on the standard output"
echo >&3 "This will appear in foo.out"
echo "This will appear both on standard output and in foo.out" | tee /dev/fd/3
(/dev/fd is not supported everywhere; it's available at least on Linux, *BSD, Solaris and Cygwin.)