I am creating a script to automate partitioning of a harddrive.
Now I am having trouble with the following stuff:
I need to check if a "." exists in a text file. (so just the dot).
What is the best way to accomplish this?.
Example:
hdhelft=`cat /sometextfile`
if grep "." $hdhelft
then
hdhelf2=something
fi
No need to read the file into a variable unless that's what you really want. It's not entirely clear from your code what you want, but here's my interpretation. Use the -F flag to grep to get it to interpret the . as a literal, and the -q so it doesn't give any output (just yes or no). Also, if you really want $hdhelft to contain the contents of the file, use $(<filename) to get that.
hdhelft=$(</sometextfile)
if grep -qF '.' /sometextfile; then
hdhelf2=something
fi
You need to escape the . character as grep interprets that as "any character". So use:
grep '\.' yourfile
Related
Guys i have a string like this:
variable='<partyRoleId>12345</partyRoleId>'
what i want is to extract the value so the output is 12345.
Note the tag can be in any form:
<partyRoleId> or <ns1:partyRoleId>
any idea how to get the tag value using grep or sed only?
Use an XML parser to extract the value:
echo "$variable" | xmllint -xpath '*/text()' -
You probably should use it for the whole XML document instead of extracting a single line from it into a variable, anyway.
to use only grep, you need regexp to find first closing brackets and cut all digits:
echo '<partyRoleId>12345</partyRoleId>'|grep -Po ">\K\d*"
-P means PCRE
-o tells to grep to show only matched pattern
and special \K tells to grep cut off everything before this.
I'm getting the size of a file from a remote webserver and saving the results to a var called remote I get this using:
remote=`curl -sI $FILE | grep -i Length | awk '/Content/{print $(NF-0)}'`
Once I've downloaded the file I'm getting the local files size with:
local=`stat --print="%s" $file`
If I echo remote and local they contain the same value.
I'm trying to run an if statement for this
if [ "$local" -ne "$remote" ]; then
But it always shows the error message, and never advises they match.
Can someone advise what I'm doing wrong.
Thanks
curl's output uses the network format for text, meaning that lines are terminated by a carriage return followed by linefeed; unix tools (like the shell) expect lines to end with just linefeed, so they treat the CR as part of the content of the line, and often get confused. In this case, what's happening is that the remote variable is getting the content length and a CR, which isn't valid in a numeric expression, hence errors. There are many ways to strip the CR, but in this case it's probably easiest to have awk do it along with the field extraction:
remote=$(curl -sI "$remotefile" | grep -i Length | awk '/Content/{sub("\r","",$NF); print $NF}')
BTW, I also took the liberty of replacing backticks with $( ) -- this is easier to read, and doesn't have some oddities with escapes that backticks have, so it's the preferred syntax for capturing command output. Oh, and (NF-0) is equivalent to just NF, so I simplified that. As #Jason pointed out in a comment, it's safest to use lower- or mixed-case for variable names, and put double-quotes around references to them, so I did that by changing $FILE to "$remotefile". You should do the same with the local filename variable.
You could also drop the grep command and have awk search for /^Content-Length:/ to simplify it even further.
I have the following IP addresses in a file
3.3.3.1
3.3.3.11
3.3.3.111
I am using this file as input file to another program. In that program it will grep each IP address. But when I grep the contents I am getting some wrong outputs.
like
cat testfile | grep -o 3.3.3.1
but I am getting output like
3.3.3.1
3.3.3.1
3.3.3.1
I just want to get the exact output. How can I do that with grep?
Use the following command:
grep -owF "3.3.3.1" tesfile
-o returns the match only and not the whole line.-w greps for whole words, meaning the match must be enclosed in non word chars like <space>, <tab>, ,, ; the start or the end of the line etc. It prevents grep from matching 3.3.3.1 out of 3.3.3.111.
-F greps for fixed strings instead of patterns. This prevents the . in the IP address to be interpreted as any char, meaning grep will not match 3a3b3c1 (or something like this).
To match whole words only, use grep -ow 3.3.3.1 testfile
UPDATE: Use the solution provided by hek2mgl as it is more robust.
You may use anhcors.
grep '^3\.3\.3\.1$' file
Since by default grep uses regex, you need to escape the dots in-order to make grep to match literal dot character.
On Mac (OS X) I have a directory with many images named like this:
IMG_250x333_1.jpg
IMG_250x333_2.jpg
IMG_250x333_3.jpg
...
I need to rename all of them to:
IMG_1.jpg
IMG_2.jpg
IMG_3.jpg
...
I think using a UNIX command line with "mv" and a kind of regex would do the job, but I don't know how! Can someone please help?
Thanks!
What happens if there's a IMG_111x333_1.jpg and also a IMG_444x222_1.jpg? You risk mangling/overwriting something...
But if that is what you want, you can do it like this:
#!/bin/bash
for f in *.jpg; do
new=${f/_*_/_}
echo mv "$f" $new
done
If you like what it is doing, remove the word echo.
Here's an approach I like:
ls | sed 's/\(.*\)250x333_\(.*\)/mv "&" "\1\2"/' | sh
List the files with ls.
Then, transform the filenames with sed, and generate a mv command. Note that the & in the sed command outputs the full input string.
Finally, evaluate the mv command with sh
The nice thing about this approach is you can remove | sh and test that your regex is correct.
Let's say that I have the following text in a file:
foo.bar.baz
bar.baz
123.foo.bar.baz
pqr.abc.def
xyz.abc.def
abc.def.ghi.jkl
def.ghi.jkl
How would I remove duplicates from the file, on the basis of postfixes? The expected output without duplicates would be:
bar.baz
pqr.abc.def
xyz.abc.def
def.ghi.jkl
(Consider foo.bar.baz and bar.baz. The latter is a substring postfix so only bar.baz remains. However, neither of pqr.abc.def and xyz.abc.def are not substring postfixes of each other, so both remain.)
Try this:
#!/bin/bash
INPUT_FILE="$1"
in="$(cat $INPUT_FILE)"
out="$in"
for line in $in; do
out=$(echo "$out" | grep -v "\.$line\$")
done
echo "$out"
You need to save it to a script (e.g. bashor.sh), make it executable (chmod +x bashor.sh) and call it with your input file as the first argument:
./bashor.sh path/to/input.txt
Use sed to escape the string for regular expressions, prefix ., postfix $ and pipe this into GNU grep (-f - doesn't work with BSD grep, eg. on a mac).
sed 's/[^-A-Za-z0-9_]/\\&/g; s/^/./; s/$/$/' test.txt |grep -vf - test.txt
I just used to regular expression escaping from another answer and didn't think about whether it is reasonable. On first sight it seems fine, but escapes too much, though probably this is not an issue.