I am writing a script where I need to list files without displaying them. The below script list the files while executing which I don't want to do. Just want to check if there are files in directory then execute "executing case 2".
ls -lrt /a/b/c/
if [ $? != 0 ]
then
echo "executing case 2"
else
echo "date +%D' '%TNo files found to process" >> $LOG
Testing the return code of ls won't do you a lot of good, because it'll return zero in both cases where it could list the directory.
You could do so with grep though.
e.g.:
ls | grep .
echo $?
This will be 'true' if grep matched anything (files were present). And false if not.
So in your example:
ls | grep .
if [ $? -eq 0 ]
then
echo "Directory has contents"
else
echo "directory is empty"
fi
Although be cautious with doing this sort of thing - it looks like you're in danger of a busy-wait test, which can make sysadmins unhappy.
If you don't need to see the output of ls, you could just make it a condition:
[ "$(ls -lrt a/b/c)" ] && echo "Not Empty" || echo "Empty"
Or better yet
[ "$(ls -A a/b/c)" ] && echo "Not Empty" || echo "Empty"
Since you don't care about long output (l) or display order (rt).
In a script, you could use this in an if statement:
#!/bin/sh
if [ "$(ls -A a/b/c)" ]; then
echo "Not empty"
else
echo "Empty"
fi
Related
Have two files:
file1 is having the key words - INFO ERROR
file2 is having the list of log files path - path1 path2
I need to exit out of the script if any of the condition in any of the loops failed.
Here is the Code:
#!/bin/bash
RC=0
while read line
do
echo "grepping from the file $line
if [ -f $line ]; then
while read key
do
echo "searching $key from the file $line
if [ condition ]; then
RC=0;
else
RC=1;
break;
fi
done < /apps/file1
else
RC=1;
break;
fi
done < apps/file2
exit $RC
Thank you!
The ansewer to your question is using break 2:
while true; do
sleep 1
echo "outer loop"
while true; do
echo "inner loop"
break 2
done
done
I never use this, it is terrible when you want to understand or modify the code.
Already better is using a boolean
found_master=
while [ -n "${found_master}" ]; do
sleep 1
echo "outer loop"
while true; do
echo "inner loop"
found_master=true
break
done
done
When you do not need the variable found_master it is an ugly additional variable.
You can use a function
inner_loop() {
local i=0;
while ((i++ < 5)); do
((random=$RANDOM%5))
echo "Inner $i: ${random}"
if [ ${random} -eq 0 ]; then
echo "Returning 0"
return 0
fi
done;
return 1;
}
j=0
while ((j++ < 5 )); do
echo "Out loop $j"
inner_loop
if [ $? -eq 0 ]; then
echo "inner look broken"
break
fi
done
But your original problem can be handles without two while loops.
You can use grep -E "INFO|ERROR" file2 or combining the keywords. When the keywords are on different lines in file1, you can use grep -f file1 file2.
Replace condition with $(grep -c ${key} ${line}) -gt 0 like this:
echo "searching $key from the file $line
if [ $(grep -c ${key} ${line}) -eq 0 ]; then
It will count the each key-word in your log-file. If count=0 (pattern didn't found), running then. If found at least 1 key, running else, RC=1 and exit from loop.
And be sure, that your key-words can't be substrings of the longest words, or you will get an error.
Example:
[sahaquiel#sahaquiel-PC Stackoverflow]$ cat file
correctstringERROR and more useless text
ERROR thats really error string
[sahaquiel#sahaquiel-PC Stackoverflow]$ grep -c ERROR file
2
If you wish to avoid count 2 (because counting first string, obliviously, bad way), you should also add two keys for grep:
[sahaquiel#sahaquiel-PC Stackoverflow]$ grep -cow ERROR file
1
Now you have counted only the words equal to your key, not substrings in any useful strings.
If the argument is 0 then script should check directory called “App0” is in the windows path variable. If not exists, then add \App0 in the path. I Am Struggling To Understand ( If the argument is 0 ).
My Work So Far.
if [ -d "${Appo}" ]; then
echo "Appo Doesn't Exist."
mkdir Appo
echo "File Created"
fi
Thank You
#!/bin/sh
if [[ $# == 0 ]]
then
echo "zero args"
fi
for arg in "$#" # You might get more than one argument.
do
dir="App${arg}" # Make the name by combining the strings.
if [[ -d $dir ]]
then
echo "App$arg exists"
else
mkdir "$dir" # Be careful the name supplied may contain spaces.
echo "Created directory: $dir"
fi
done
###Takes filenames as arguments and makes those executable
#create file variable
file=$*
chmod 755 $file
if [ $? -eq 0 ] ; then
echo permission change suceeded
else
echo permission change failed
exit 0
fi
This is my current code - I'm wanting to add an extra echo which will be "already got executable permission" - how would i add a check onto this to check that if it has executable permission or not
if [ -x "$file" ]; then
echo "already got executable permission"
else
....
fi
Check
help test
perm="$(stat -c "%a" $file)"
if [$perm -eq 755]; then
...
else
...
fi
How to write a shell script named "backup.sh" which accepts one parameter, which would be a filename/directory.
Create a backup copy of that with the .bak appended to its name.Show message on success.
If the file/directory does not exist, show a proper message.
i did up to this point.please help me to figure this out
#!/bin/sh
#create_backup.sh
And add a .bak
bak="${backup.sh}.bak"
if [ "$#" -eq 0 ]
then
exit 1;
echo "File Succesfully backuped"
fi
cp ${1} "${1}.back"
echo "File is not found "
exit 0
#!/bin/bash -e
directory=$1
cp -r $directory $directory.bak
echo "Success"
obvious caveats with pathing/error codes/etc
why in Cygwin Terminal - the if statement work
and ubuntu - unix - not working for
this code :
#!/bin/sh
valid_password="pass"
echo "Please enter the password:"
read password
if [ "$password" == "$valid_password" ]
then
echo "You have access!"
else
echo "Access denied!"
fi
#emil pointed the answer:
if [ "$password" = "$valid_password" ]
instead of
if [ "$password" == "$valid_password" ]
Also: did you give the script executing permissions? Try
chmod +x script_name
because the correct syntax to [ is:
[ a = b ]
From your error message it sounds like you wrote:
if ["$password" = "$valid_password" ]
change this to:
if [ "$password" = "$valid_password" ]
notice the space after [. if just takes a shell command, try to run it and depending if the exit code from the program is 0 it will run the commands inside the if statement.
In your terminal, write i.e.:
user#localhost$ true; echo $?
0
to test your if statement:
user#localhost$ pass=pass; valid=pass
user#localhost$ if [ "$pass" = "$valid" ]; then echo 'You have access!'; fi
As #nullrevolution said, the ! is evaluated if you use double quotes, it will try to run last command in your shell history, in this case that is matching u.
user#localhost$ uname
Linux
user#localhost$ !u
uname
Linux
user#localhost$ echo "!"
sh: !: event not found
This is because the ! is evaluated before the double quotes are matched, and echo is run. If you still want to use double quotes, you will have to escape the ! outside the quotes:
echo "Access denied"\!
#nullrevolution also said you could try with bash, which has a builtin syntax for the expression inside if statements.
#!/bin/bash
valid_password=pass
echo "Please enter the password:"
read password
if [[ "$password" == "$valid_password" ]]; then
echo 'You have access!'
else
echo 'Access denied!'
fi
Also in your program I guess you do not want to echo the password in the terminal, to turn off echo temporary change:
read password
to
stty -echo
read password
stty echo
if you forgot to write stty echo to turn on echo again, just write reset in your terminal, and it will reset the terminal to default settings.
A useful tutorial for bourn shell script can be found here:
http://www.grymoire.com/Unix/Sh.html