I'm running into an issue where my argument list for echo is too long and would like some ideas on how to get around this issue, or at least test for the condition so I can properly handle it, and it won't kill my script
for file in `cat filelist`; do
PROTOCOLS1=`egrep -i 'rsh|rsync|remsh' "$file" | egrep -v '^[ | ]*#'`
FIELDS=`echo $PROTOCOLS1|wc -l`
if [[ $FIELDS -gt 1024 ]]; then
echo $file >> $debuglog
else
set -A myarray $PROTOCOLS1
do stuff.....
fi
done
So the problem is that when my arg list for echo is too long, $FIELDS is set to null, and thus my test for $FIELDS -gt 1024 always is true and does not get caught.
Problem is when it goes to the array it's obviously too big and I get a subscript out of range error and my script exits.
Any ideas are greatly appreciated.
Edit 9/18
OK so the problem is a little more basic.
myserver-v1> echo $variable
myserver-v1> /usr/bin/echo: too many args
I want to test for this in my script
I tried the following, which works, but I get all this crap to stdout, which fills up my debug log and is annoying
echo $variable
if [[ $? -ne 0 ]]; then
write to error log
fi
Is there a way to test echo $variable....without sending it to stdout?
I tried the following, but neither seemed to work, so I am kind of at a loss here.
[[ ! `echo $variable ]]
[[ `echo $variable ]]
If you keep the unquoted variable $PROTOCOLS1 in the echo, you could simplify life by replacing:
FIELDS=`echo $PROTOCOLS1|wc -l`
with
FIELDS=1
This is because when you echo $PROTOCOLS1 without any quotes around it, you will only have one (possibly very long) line of output. Alternatively, you can use:
FIELDS=$(echo "$PROTOCOLS1" | wc -l)
where the double quotes will preserve the newlines in the value of PROTOCOLS1 (but it gets you back to the 'argument list too long' problem).
So, you need to think about using:
FIELDS=$(egrep -i 'rsh|rsync|remsh' "$file" | egrep -c -v '^[ | ]*#')
which gets the second egrep to do the line counting for you. Obviously, since the later portion of the script uses $PROTOCOLS1, you will need to re-evaluate the egreps to get the data, but you should think about whether your processing scheme is appropriate. If you are running into a string value that is too long, you are probably not doing the processing in the best way. What the alternatives are depends on what you are trying to do, and the question does not reveal that. It might be appropriate to do the extra processing with a scripting language such as Perl, Python or Ruby.
Related
The script found error but it always goes to Else condition "No Found Error". Am I missing how to compare two variables?
ERROR="Error:"
for i in `find /logs -mtime -1`
do
CHECK=`cat $i |grep -i "Error"|cut -f 1 -d " "`
if [ "$CHECK" == $ERROR ]
then
echo "Found Error"
else
echo "Not Found Error"
fi
done
Did you tried something like if [[ "$CHECK" == $ERROR ]] ?
To simply detect error without printing the error message, you can use
CHECK=$(cat $i | grep "Error" | wc -l)
if [[ $CHECK -ne 0 ]]
then
echo "Found error"
else
echo "Not found error"
fi
You are using grep -i for case-insensitive matching, but then testing the result for exact equality with the string Error:. If the case-insensitive matching is important then the exact equality test is not an appropriate complement.
You are also capturing a potentially multi-line output and comparing it to a string that can be the result only of a single-line output.
And you are matching "Error:" anywhere on the line, but assuming that it will appear at the beginning.
Overall, you are going about this a very convoluted way, as grep tells you via its exit status whether it found any matches. For example:
#!/bin/bash
for log in `find /logs -mtime -1`; do
if grep -i -q '^Error:' "$log"; then
echo "Found Error"
else
echo "Not Found Error"
fi
done
There is two things that I would advise and may fix your issue:
Add #!/bin/bash on the first line, to make sure it is interpreted as bash and not sh. Many time I had trouble with comparison because of this
When comparing two variables, uses double brackets ([[ and ]]) Also, if it strings, always put quotes "$ERROR" around it. It's missing for the $ERROR variable.
Look at the other answers also, there are many ways to do the same thing in a much simpler way.
Note: When comparing numbers you should use -eq
In a bash script, I have a list of lines in a file I wish to grep and then display on standard out, which is easiest done with a while read:
grep "regex" "filepath" | while read line; do
printf "$line\n"
done
However, I would like to inform the user if no lines were matched by the grep. I know that one can do this by updating a variable inside the loop but it seems like a much more elegant approach (if possible) would be to try to read a line in an until loop, and if there were no output, an error message could be displayed.
This was my first attempt:
grep "regex" "filepath" | until [[ -z ${read line} ]]; do
if [[ -z $input ]]; then
printf "No matches found\n"
break
fi
printf "$line\n"
done
But in this instance the read command is malformed, and I wasn't sure of another way the phrase the query. Is this approach possible, and if not, is there a more suitable solution to the problem?
You don't need a loop at all if you simply want to display a message when there's no match. Instead you can use grep's return code. A simple if statement will suffice:
if ! grep "regex" "filepath"; then
echo "no match" >&2
fi
This will display the results of grep matches (since that's grep's default behavior), and will display the error message if it doesn't.
A popular alternative to if ! is to use the || operator. foo || bar can be read as "do foo or else do bar", or "if not foo then bar".
grep "regex" "filepath" || echo "no match" >&2
John Kugelman's answer is the correct and succinct one and you should accept it. I am addressing your question about syntax here just for completeness.
You cannot use ${read line} to execute read -- the brace syntax actually means (vaguely) that you want the value of a variable whose name contains a space. Perhaps you were shooting for $(read line) but really, the proper way to write your until loop would be more along the lines of
grep "regex" "filepath" | until read line; [[ -z "$line" ]]; do
... but of course, when there is no output, the pipeline will receive no lines, so while and until are both wrong here.
It is worth amphasizing that the reason you need a separate do is that you can have multiple commands in there. Even something like
while output=$(grep "regex filepath"); echo "grep done, please wait ...";
count=$(echo "$output" | wc -l); [[ $count -gt 0 ]]
do ...
although again, that is much more arcane than you would ever really need. (And in this particular case, you would want probably actually want if , not while.)
As others already noted, there is no reason to use a loop like that here, but I wanted to sort out the question about how to write a loop like this for whenever you actually do want one.
As mentioned by #jordanm, there is no need for a loop in the use case you mentioned.
output=$(grep "regex" "file")
if [[ -n $output ]]; then
echo "$output"
else
echo "Sorry, no results..."
fi
If you need to iterate over the results for processing (rather than just displaying to stdout) then you can do something like this:
output=$(grep "regex" "file")
if [[ -n $output ]]; then
while IFS= read -r line; do
# do something with $line
done <<< "$output"
else
echo "Sorry, no results..."
fi
This method avoids using a pipeline or subshell so that any variable assignments made within the loop will be available to the rest of the script.
Also, i'm not sure if this relates to what you are trying to do at all, but grep does have the ability to load patterns from a file (one per line). It is invoked as follows:
grep search_target -f pattern_file.txt
I'm writing a shell script that greps for $foo then counts the number of occurrences then runs a command. Each time that command is run, there is one less instance of $foo in that file. Uncertain on how to continuously read that file and reduce the value in the variable I set.
$count= `grep -o $foo /some/file |wc -w`
until [ $count -eq 0 ]
do
some_command_that_deletes_foo_in_file
done
However I realize that $count is set once at runtime and is not updated. What I want is $count to be updated to the current count in /some/file while the script is looping through /some/file until there is 0 instances of the phrase I'm grepping for. Uncertain to what the best approach is.
Unless you have additional code that you haven't showed us that depends on $count, you don't actually need to count occurrences; you just need to know whether the string appears in the file. For that, you can write:
while grep -q -- "$foo" /some/file ; do
some_command_that_deletes_foo_in_file
done
(using the fact that grep returns success when it finds the value, and failure when it does not, and using the -q flag to suppress its console output).
You could add the grep command inside the loop:
count=$(grep -o "$foo" /some/file |wc -w)
until (( count == 0 ))
do
some_command_that_deletes_foo_in_file
count=$(grep -o "$foo" /some/file |wc -w)
done
You simply want to delete the string "$foo"? Use sed:
sed "/$foo/d" /some/file > /some/other/file
The sed command is an editor. The /$foo/ is taking a regular expression (whatever the value of $foo), finding it in the file. The d tells it to delete the line.
sed doesn't usually do an in place edit. You usually have to write to another file and then to a move. However, some sed commands may have such a parameter. You can check your manage.
Second Try
I think it must take some action or perform some processing or something, and one of its effects is that one of the $foos is gone. (But I could be wrong.) – ruakh yesterday
This is what I get answering these questions at night.
You can take advantage of the fact that grep returns true (i.e. exit value = 0) if it can find your regular expression and false (i.e. exit value not equal to 0) otherwise:
while grep -o -q "$foo" "/some/file"
do
some_command_that_deletes_foo_in_file
done
The -q tells grep not to output anything. Instead, the exit value of grep will be true if the string is found and false if it isn't.
Read your manpage on grep. Some grep commands don't have the -q parameter. In that case, you'l need to redirect both STDOUT and STDERR to /dev/null.
Another tact may be to do your count of the number of lines, and then use that as a counter:
count=$(grep -o "$foo" "/some/file" | wc -w) # $(...) is the preferred syntax over `...`
for loop in {1..$count}
do
some_command_that_deletes_foo_in_file
done
The advantage is that you only grep through the file once (which maybe a long operation). However, your count maybe incorrect if $foo is on more than one line.
A few notes:
The $(...) is preferred over backticks
When you set a variable, you don't use the dollar sign in front of that variable. Note I have count= and not $count=.
Watch spaces. count= $(...) is wrong because there's a space after the equals sign.
So I am writing a script that will curl a site I've written that will return a string. I am using it to compare a value that is saved within a file. I am having trouble getting my conditional statement to return true for matching values.
Here is a snippet of my bash code
var1=$(curl -s -w %{http_code}\\n www.somesite.com)
var2=$(cat somefile)
if [[ "$var1" = "$var2" ]]; then
echo "TRUE"
else
echo "FALSE"
fi
I have manually looked at both the strings and they seem to be identical. I've done wc with all applicable options with it. I've copy and pasted both the values into Notepad++ and did a find for the expected string and it said that both values matched the find command.
Obviously, if I manually put the values in the condition it returns true, so I know its not my conditional statement.
My guess is there is some type of hidden character on the end of curl...('\r' or '\n' or something that I am unaware)...or maybe on the end of the file that I am unaware of. Is this a known issue when trying to compare curl output and file content?
This may be a dumb question, but for the life of me I cannot seem to get these strings to match doing it dynamically instead of hardcoding the values in the condition.
Any suggestions would be great. Thanks
$ diff -q -b <(echo $'abc\ndef') <(echo $'abc\r\ndef') > /dev/null ; echo $?
0
$ diff -q -b <(echo $'abc\ndef') <(echo $'abc\r\nde') > /dev/null ; echo $?
1
Shell script snippet:
tagSearch= $(grep '^\#ctags$' ./"$1" | wc -l)
if [[ $tagSearch -ne "0" ]]
then
...
fi
Results in:
line 2: /bb/bin/1: Permission denied
Context:
I'm trying to detect whether a particular pattern exists in a file so I can take a particular action.
I understand the error I'm getting, the detection is working but the script is trying to evaluate the result '1' and run the program '1' in my path. This isn't what I want. How do I get the behavior I'm looking for?
The problem is
tagSearch= $(grep '^\#ctags$' ./"$1" | wc -l)
----------^
You can't use spaces around the equal sign; what you're actually doing here is to temporarily set tagSearch to the empty string in the environment, then invoking grep '^\#ctags$' ./"$1" | wc -l, then trying to run that as a command since the $() will have inserted the result into the command line.
tagSearch=$(grep '^\#ctags$' ./"$1" | wc -l)
Variable assignments in the bash shell should not have a space after the equals. Actually it should never have whitespace in it at all. See below.
tagSearch=$(grep '^\#ctags$' "./$1" | wc -l)
if [[ $tagSearch -ne 0 ]]
then
...
fi
Not important to your error but also of note, when using the double bracket syntax, you don't need to quote that zero any more than the variable you are comparing it with.
Actually your whole code could be re-factored using grep's quite mode and evaluating the return code to see if you got any matches:
if grep '^\#ctags$' "./$1"
then
...
fi
Actually you can have that simpler, because the return code of grep will be 0 if something is found (1 otherwise), so you don't need wc -l. And you can just write:
if `grep -q pattern file`; then echo "yes"; else echo "no"; fi;