I am not sure why touch filename{1..10} is not working in my k-shell?
Does it necessary to make a loop in this case? If so what is wrong here:
#!/usr/bin/ksh
for i in {1..10}
do
touch file${i}
done
Thanks !!
The original touch file[i] creates a single file with the name "file[i]".
$ touch file[i]
$ ls
file[i]
$
As Sun's older ksh88 dialect does not understand brace expansion, you need to use something like:
i=1 && while ((i<=10)); do
((i+=1))
touch filename${i}
done
Related
I have a number of files with the following naming:
name1.name2.s01.ep01.RANDOMWORD.mp4
name1.name2.s01.ep02.RANDOMWORD.mp4
name1.name2.s01.ep03.RANDOMWORD.mp4
I need to remove everything between the last . and ep# from the file names and only have name1.name2.s01.ep01.mp4 (sometimes the extension can be different)
name1.name2.s01.ep01.mp4
name1.name2.s01.ep02.mp4
name1.name2.s01.ep03.mp4
This is a simpler version of #Jesse's [answer]
for file in /path/to/base_folder/* #Globbing to get the files
do
epno=${file#*.ep}
mv "$file" "${file%.ep*}."ep${epno%%.*}".${file##*.}"
#For the renaming part,see the note below
done
Note : Didn't get a grab of shell parameter expansion yet ? Check [ this ].
Using Linux string manipulation (refer: http://www.tldp.org/LDP/abs/html/string-manipulation.html) you could achieve like so:
You need to do per file-extension type.
for file in <directory>/*
do
name=${file}
firstchar="${name:0:1}"
extension=${name##${firstchar}*.}
lastchar=$(echo ${name} | tail -c 2)
strip1=${name%.*$lastchar}
lastchar=$(echo ${strip1} | tail -c 2)
strip2=${strip1%.*$lastchar}
mv $name "${strip2}.${extension}"
done
You can use rename (you may need to install it). But it works like sed on filenames.
As an example
$ for i in `seq 3`; do touch "name1.name2.s01.ep0$i.RANDOMWORD.txt"; done
$ ls -l
name1.name2.s01.ep01.RANDOMWORD.txt
name1.name2.s01.ep02.RANDOMWORD.txt
name1.name2.s01.ep03.RANDOMWORD.txt
$ rename 's/(name1.name2.s01.ep\d{2})\..*(.txt)$/$1$2/' name1.name2.s01.ep0*
$ ls -l
name1.name2.s01.ep01.txt
name1.name2.s01.ep02.txt
name1.name2.s01.ep03.txt
Where this expression matches your filenames, and using two capture groups so that the $1$2 in the replacement operation are the parts outside the "RANDOMWORD"
(name1.name2.s01.ep\d{2})\..*(.txt)$
I have the following hacking-challenge, where we don't know, if there is a valid solution.
We have the following server script:
read s # read user input into var s
echo "$s"
# tests if it starts with 'a-f'
echo "$s" > "/home/user/${s}.txt"
We only control the input "$s". Is there a possibility to send OS-commands like uname or do you think "no way"?
I don't see any avenue for executing arbitrary commands. The script quotes $s every time it is referenced, so that limits what you can do.
The only serious attack vector I see is that the echo statement writes to a file name based on $s. Since you control $s, you can cause the script to write to some unexpected locations.
$s could contain a string like bob/important.txt. This script would then overwrite /home/user/bob/important.txt if executed with sufficient permissions. Sorry, Bob!
Or, worse, $s could be bob/../../../etc/passwd. The script would try to write to /home/user/bob/../../../etc/passwd. If the script is running as root... uh oh!
It's important to note that the script can only write to these places if it has the right permissions.
You could embed unusual characters in $s that would cause irregular file names to be created. Un-careful scripts could be taken advantage of. For example, if $s were foo -rf . bar, then the file /home/user/foo -rf . bar.txt would be created.
If someone ran for file in /home/user; rm $file; done they'd have a surprise on their hands. They would end up running rm /home/user/foo -rf . bar.txt, which is a disaster. If you take out /home/user/foo and bar.txt you're left with rm -rf . — everything in the current directory is deleted. Oops!
(They should have quoted "$file"!)
And there are two other minor things which, while I don't know how to take advantage of them maliciously, do cause the script to behave slightly differently than intended.
read allows backslashes to escape characters like space and newline. You can enter \space to embed spaces and \enter to have read parse multiple lines of input.
echo accepts a couple of flags. If $s is -n or -e then it won't actually echo $s; rather, it will interpret $s as a command-line flag.
Use read -r s or any \ will be lost/missinterpreted by your command.
read -r s?"Your input: "
if [ -n "${s}" ]
then
# "filter" file name from command
echo "${s##*/}" | sed 's|^ *\([[:alnum:]_]\{1,\}\)[[:blank:]].*|/home/user/\1.txt|' | read Output
(
# put any limitation on user here
ulimit -t 5 1>/dev/null 2>&1
`${read}`
) > ${OutPut}
else
echo "Bad command" > /home/user/Error.txt
fi
Sure:
read s
$s > /home/user/"$s".txt
If I enter uname, this prints Linux. But beware: this is a security nightmare. What if someone enters rm -rf $HOME? You'd also have issues with commands containing a slash.
I know this question has been asked numerous times, but I still could not find any good solution. Hence, asking it again if anyone can help !!
I am trying to change a my working directory inside a shell script with help of a variable. But I get " No such file or directory" everytime.
#!/bin/bash
echo ${RED_INSTANCE_NAME} <-- This correctly displays the directory name
cd $RED_INSTANCE_NAME <-- This line gives the error
Now, when I try to give the actually directory name instead of using the variable, shell changes the directory without issues
cd test <-- No error
Does anyone knows what can be the issue here ? Please help !!
You variable contains a carriage return. Try saying:
cd $(echo $RED_INSTANCE_NAME | tr -d '\r')
and it should work. In order to remove the CR from the variable you can say:
RED_INSTANCE_NAME=$(echo $RED_INSTANCE_NAME | tr -d '\r')
The following would illustrate the issue:
$ mkdir abc
$ foo=abc$'\r'
$ echo "${foo}"
abc
$ cd "${foo}"
: No such file or directory
$ echo $foo | od -x
0000000 6261 0d63 000a
0000005
$ echo $foo | tr -d '\r' | od -x
0000000 6261 0a63
0000004
$ echo $'\r' | od -x
0000000 0a0d
0000002
One way to encounter your described problem is to have a tilde (~) in the variable name. Use the absolute path or $HOME variable instead. Note that using $HOME will require double quotations.
# doesn't work
$ vartilde='~/'
$ cd $vartilde
-bash: cd: ~: No such file or directory
# works
$ varfullpath='/Users/recurvirostridae'
$ cd $varfullpath
# works
$ varwithhome="$HOME"
$ cd $varwithhome
Try
cd "$RED_INSTANCE_NAME"
Also, make sure the path makes sense to the current directory where cd command is executed.
I ran into a different issue. My "cd $newDir" was failing because I added logging into my script. Apparently if you add a pipe to any cd command it does nothing or gets gobbled up.
Wasted 3 hours figuring that out.
newDir=$oldDir/more/dirs/
cd $newDir #works
cd $newDir | tee -a log #does nothing
cd $newdir | echo hi #does nothing
So cd with any pipe does nothing. No idea why cd fails. The pipe means finish what command you doing then feed any output to next command. This is on RHEL 7.
I was trying to log all my commands and hit this nice error. Figured I'd post it in case anyone else hits it.
You can check for carriage returns, ANSI escapes and other special characters with
cat -v <<< "$RED_INSTANCE_NAME"
This will show all the characters that echo $RED_INSTANCE_NAME would just hide or ignore.
In particular, if your error message is : No such file or directory as opposed to bash: cd: yourdir: No such file or directory, it means you have a carriage return at the end of your variable, probably from reading it from a DOS formatted file.
I don't know what is going wrong for you, but I can offer one piece of general advice:
cd "$RED_INSTANCE_NAME" # Quote the string in case it has spaces.error
You should nearly always put the "$VARIABLE" in quotes. This will protect from surprises when the value of the variable contains funny stuff (like spaces).
I have a set of files that come in pairs:
/var/log/messages-20111001
/var/log/messages-20111001.hash
I've had several of these rotate away and now I'm left with a ton of /var/log/messages-201110xx.hash files with no associated log. I'd like to clean up the mess, but I'm uncertain how to remove a file that isn't part of a "pair". I can use bash or zsh (or any LSB tool, really). I need to remove all the .hash files that don't have an associated log.
Example
/var/log/messages-20111001.hash
/var/log/messages-20111002.hash
/var/log/messages-20111003.hash
/var/log/messages-20111004.hash
/var/log/messages-20111005
/var/log/messages-20111005.hash
/var/log/messages-20111006
/var/log/messages-20111006.hash
Should be reduced to:
/var/log/messages-20111005
/var/log/messages-20111005.hash
/var/log/messages-20111006
/var/log/messages-20111006.hash
for file in *.hash; do test -f "${file%.hash}" || rm -- "$file"; done
Something like this?
for f in /var/log/messages-????????.hash ; do
[[ -e "${f%.hash}" ]] || rm "$f"
done
I want to tail multiple files (and follow them) in CentOS, I've tried this:
tail -f file1 file2 file3
but the output is very unfriendly
I've also had a look at multitail but can't find a CentOS version.
What other choices do I have?
Multitail is available for CentOS in rpmforge repos. To add rpmforge repository check the documentation on 3rd Party Repositories.
I found the solution described here work well on centos:
The link is http://www.thegeekstuff.com/2009/09/multitail-to-view-tail-f-output-of-multiple-log-files-in-one-terminal/
Thanks to Ramesh Natarajan
$ vi multi-tail.sh
#!/bin/sh
# When this exits, exit all back ground process also.
trap 'kill $(jobs -p)' EXIT
# iterate through the each given file names,
for file in "$#"
do
# show tails of each in background.
tail -f $file &
done
# wait .. until CTRL+C
wait
You could simulate multitail by opening multiple instances of tail -f in Emacs subwindows.
I usually just open another xterm and run a separate 'tail -f' there.
Otherwise if I'm using the 'screen' tool, I'll set up separate 'tail -f' commands there. I don't like that as much because it takes a few keystrokes to enable scrolling in screen before using the Page Up and Page Down keys. I prefer to just use xterm's scroll bar.
You can use the watch command, i use it to tail two files at the same time:
watch -n0 tail -n30 file1 file2
A better answer to an old question...
I create a shell function in my .bashrc (obviously assumes you're using bash as your shell) and use tmux. You can probably complicate this a whole lot and do it without the tempfile, but the quoting is just ugly if you're trying to ensure that files with spaces or other weird characters in the name still work.
multitail ()
{
cmdfile=`mktemp`
echo "new-session -d \"tail -f '$1'\"" >$cmdfile
shift
for file in "$#"
do
echo "split-window -d \"tail -f '$file'\"" >>$cmdfile
done
echo "select-layout even-vertical" >>$cmdfile
tmux source-file $cmdfile \; attach && rm -f $cmdfile
}