How to remove empty/blank lines from a file in Unix (including spaces)?
This sed line should do the trick: sed -i ‘/^$/d’ file.txt The -i means it will edit the file in-place.
command-line-interface
Run Oracle SQL script and exit from sqlplus.exe via command prompt
Another way is to use this command in the batch file: echo exit | sqlplus user/pass@connect @scriptname
What useful things can one add to one’s .bashrc? [closed]
I have a little script that extracts archives, I found it somewhere on the net: extract () { if [ -f $1 ] ; then case $1 in *.tar.bz2) tar xvjf $1 ;; *.tar.gz) tar xvzf $1 ;; *.bz2) bunzip2 $1 ;; *.rar) unrar x $1 ;; *.gz) gunzip $1 ;; *.tar) tar xvf $1 … Read more
Find out symbolic link target via command line
Use the -f flag to print the canonicalized version. For example: readlink -f /root/Public/myothertextfile.txt From man readlink: -f, –canonicalize canonicalize by following every symlink in every component of the given name recursively; all but the last component must exist
How do I find the UUID of a filesystem
Another command that might be available and also works quite well for this is ‘blkid’. It’s part of the e2fsprogs package. Examples of it’s usage: Look up data on /dev/sda1: topher@crucible:~$ sudo blkid /dev/sda1 /dev/sda1: UUID=”727cac18-044b-4504-87f1-a5aefa774bda” TYPE=”ext3″ Show UUID data for all partitions: topher@crucible:~$ sudo blkid /dev/sda1: UUID=”727cac18-044b-4504-87f1-a5aefa774bda” TYPE=”ext3″ /dev/sdb: UUID=”467c4aa9-963d-4467-8cd0-d58caaacaff4″ TYPE=”ext3″ Show UUID data … Read more
Run a .bat file in a scheduled task without a window
You could run it silently using a Windows Script file instead. The Run Method allows you running a script in invisible mode. Create a .vbs file like this one Dim WinScriptHost Set WinScriptHost = CreateObject(“WScript.Shell”) WinScriptHost.Run Chr(34) & “C:\Scheduled Jobs\mybat.bat” & Chr(34), 0 Set WinScriptHost = Nothing and schedule it. The second argument in this … Read more
How do I prevent accidental rm -rf /*?
One of the tricks I follow is to put # in the beginning while using the rm command. root@localhost:~# #rm -rf / This prevents accidental execution of rm on the wrong file/directory. Once verified, remove # from the beginning. This trick works, because in Bash a word beginning with # causes that word and all … Read more
Nginx enable site command
If you have installed the nginx package from the Ubuntu repositories, you will have two directories. /etc/nginx/sites-enabled and /etc/nginx/sites-available. In the main nginx configuration, /etc/nginx/nginx.conf, you have the following line: include /etc/nginx/sites-enabled/*.conf; So basically to list all available virtualhosts, you can run the following command: ls /etc/nginx/sites-available To activate one of them, run the following … Read more
Resolve host name from IP address
The command you are looking for is called nslookup, works fine for reverse lookups IFF someone has configured a reverse zone file, which they don’t always do.
How to cd into a directory with this name “-2” (starting with the hyphen)?
At least two ways: Use the — argument. cd — -2 This uses a convention common to GNU tools which is to not treat anything that appears after — as a command line option. As a commenter noted, this convention is also defined in the POSIX standard: Default Behavior: When this section is listed as … Read more