I have a disk from another server installed on a new server. However, when I try to make a filesystem on it, mkfs reports # mkfs -t ext4 /dev/sdd1 mke2fs 1.42.8 (20-Jun-2013) /dev/sdd1 is apparently in use by the system; will not make a filesystem here! This is a new disk to the new server….
I use curl to send requests to remote servers like following command. curl http://example.com/send –date-urlencode “data=hello” However, it is blocked by the network proxy squid in some networks with message like (some info anonymized with “…”): ERROR The requested URL could not be retrieved POST /… HTTP/1.1 Proxy-Authorization: Basic … User-Agent: Mozilla/4.0 (compatible;) Host: ……
I want to run screen on a remote host on which I do not have root/sudo privilege and screen is not installed. I can compile or copy the screen program that can run on the host. However, it reports: “Cannot make directory ‘/var/run/screen’: Permission denied” As screen is not installed on the host, the directory…
The problem is like this: I would like to send a GET request using curl and the content has spaces, such as curl “http://example.com/send?msg=hello world” The space and the “world” will be left away if this command is executed directory on Linux. How to encode spaces in curl request URL? You can use the –date-urlencode…
One of HDFS cluster’s hdfs dfsadmin -report reports: Under replicated blocks: 139016 Blocks with corrupt replicas: 9 Missing blocks: 0 The “Under replicated blocks” can be re-replicated automatically after some time. How to handle the missing blocks and blocks with corrupt replicas in HDFS? Understanding these blocks A block is “with corrupt replicas” in HDFS…
I noticed that many sites with AdSense responsive ads show large rectangle ads (336px x 280px) or large rectangle text ads (full width x 280px). However, in my own website (640px width content area), it shows most of time horizontal ones. How to make AdSense responsive ads show rectangle ads instead of horizontal ones? At…
How to find a wireless adapter‘s speed in Linux? ethtool does not show the speed of the wireless adapters. For finding the configured speed of wireless adpaters in Linux, you can use the iwconfig tool. iwconfig: configure a wireless network interface For example, to find the speed of the wireless adapter wlp8s0: # iwconfig wlp8s0…
I have a Linux box and it is connected to a network through a network adapter, say gate. How to find what is the current speed (10Mbps, 100Mbps or 1000Mbps) of the adapter? You can find the network adapter speed by the ethtool command: ethtool: query or control network driver and hardware settings For example,…
How to disable the reverse DNS lookup by the SSD server on Linux? To turn off reverse DNS lookups of the SSH daemon, log on the server and add UseDNS no to /etc/ssh/sshd_config. And remember to restart the sshd service by service sshd restart or systemctl restart sshd.service or other commands depending on your system.
What is the implementation of strstr in glibc? Implementation of STRSTR in glibc (string/strstr.c): /* Return the first occurrence of NEEDLE in HAYSTACK. Return HAYSTACK if NEEDLE is empty, otherwise NULL if NEEDLE is not found in HAYSTACK. */ char * STRSTR (const char *haystack_start, const char *needle_start) { const char *haystack = haystack_start; const…
Gmail’s SMTP is convenient. You “sender” needs not to be always your Gmail address (but the emails will include your Gmail address in the header “send by”). I am wondering how many emails at maximum can I send each day through Gmail’s SMTP. Here there a nice recent list of the sending limits of the…
How to exclude last N columns of a string in bash? The point is that the number of columns in each line is uncertain (but > N). For example, I would like to remove the last 2 columns separated by ‘.’ in the following lines. systemd.3.gz systemd.mount.3.gz systemd.mount.f.3.gz The simple cut command cut -d’.’ -f1…
Vim itself is very fast. But it turns to be slow after enabling some plugins. How to find which plugin leads the slowness of Vim? You may use the profiling mechanisms in Vim. Please check a tutorial on profiling Vim. For profiling Vim startup: vim –startuptime profile.log For profiling certain actions in Vim: :profile start…
Where can I find a list of all Xen hypervisor command line options that can be passed to Xen hypervisor during boot? This page lists all options of Xen hypervisor: Xen Hypervisor Command Line Options
YouCompleteMe for Vim on Fedora 21 reports this error: [zma@laptop:~/.vim/bundle/YouCompleteMe]$ ./install.sh — The C compiler identification is GNU 4.9.2 — The CXX compiler identification is GNU 4.9.2 — Check for working C compiler: /usr/bin/cc — Check for working C compiler: /usr/bin/cc — works — Detecting C compiler ABI info — Detecting C compiler ABI info…
I have made some eps figures for my paper but now I wanna modify them. How to edit them now? You may try inkscape on Linux: https://inkscape.org/en/ It can edit eps files.
How to redirect WordPress search query to Google CSE? You can configure Google CSE to read the query variable (by default, it is q). Then, in your WordPress’s .htaccess file, add these 2 lines RewriteCond %{QUERY_STRING} ^s=(.*)$ RewriteRule ^ https://www.google.com/cse/publicurl?cx=xyz&q=%1 [R,L] Here, “https://www.google.com/cse/publicurl?cx=xyz” is your CSE’s public URL or the webpage that contains the Google…
Unfortunately, my C: drive is almost full. Most of the space are used by the user home under C:Users. How can I move the home directory to another drive while not affecting the user’s usage of Windows. On Linux/Unix, moving the directory to another drive/partition and then keeping a softlink is enough. But how to…
My program reports that the port is already used. How to find which program or process is listening on a certain port in Linux? You can use netstat to do this. netstat can print network connections. For example, to find which program is listing on port 9999 netstat -pln | grep 9999 You will need…
How to quite VirtualBox scale mode? Use this hot key shortcut to quit VirtualBox scale mode Right_Ctrl + c