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I was recently stumped by the following error emitted from deep within a build process:
fd:4: hClose: resource vanished (Broken pipe)
It turned out to be coming from an invocation of pandoc with the --filter option, where the filter script was failing due to missing package dependencies (an artefact of the python2 → python3 transition, aargh).
A rather voracious bot which announces itself as:
Mozilla/5.0 (compatible;AspiegelBot)
and comes from a wide range of AWS IP addresses (non-exhaustive list below). It seems to be quite new and as of the time of writing there don't seem to be any meaningful search results, other than a handful of links to website statistics pages.
When logged into a server via SSH, usually any attempt to decrypt a file with GPG results in an unhelpful error message like:
gpg: cancelled by user
...
gpg: decryption failed: No secret keywith no attempt made to ask for a password.
Fix for this is simply to execute: export GPG_TTY=`tty`,
Note that if pinentry-program in ~/.gnupg/gpg-agent.conf is set to /usr/bin/pinentry-gtk, and this is an alias for /usr/bin/pinentry-gtk-2, set pinentry-program to the latter (/usr/bin/pinentry-gtk-2), which appears to change the behaviour (pinentry-gtk-2 should be able to automatically detect whether to execute in GUI or text mode, whereas the original pinentry-gtk is GUI-only.
See also "Forcing GPG passphrase input in the terminal".
My email client suddenly became unable to log in to my Gmail account with the error message:
Please log in via your web browser: https://support.google.com/mail/accounts/answer/78754 (Failure)
However I was logged in via my web browser on two different devices, and even when providing the email client with definitively the correct password, the above error recurred.
The provided link wasn't very helpful.
I started getting intermittent sets of error messages like this:
error: rpmdb: BDB0113 Thread/process 26154/140393252489024 failed: BDB1507 Thread died in Berkeley DB library
error: db5 error(-30973) from dbenv->failchk: BDB0087 DB_RUNRECOVERY: Fatal error, run database recovery
error: cannot open Packages index using db5 - (-30973)
error: cannot open Packages database in /var/lib/rpmwhen deploying changes to a bunch of AWS EC2 instances.
The error messages are misleading as (in this case at least) the RPM database is not corrupted; the underlying issue was this:
[67897.740241] Out of memory: Kill process 28759 (yum) score 330 or sacrifice child
[67905.749492] yum invoked oom-killer: gfp_mask=0x201da, order=0, oom_score_adj=0
i.e. simply a lack of memory (the instances were just too small).
The Prometheus PostgreSQL storage adapter does not seem amenable to being executed directly from a systemd service file.
As a workaround I created a wrapper script like this (adjust parameters as required):
#!/bin/bash # Wrapper to launch prometheus-postgresql-adapter, as calling # it directly from the systemd service file doesn't seem to work. # # Disclaimer: there is probably a better way of doing this. nohup /usr/local/bin/prometheus-postgresql-adapter \ -pg-host=... \ -pg-port=... \ -pg-database="..." \ -pg-user="..." \ >> /var/log/prometheus-postgresql-storage-adapter/prometheus-pg-adapter.log 2>&1
and a service file like this:
[Unit] Description=Prometheus PostgreSQL Storage Adapter Documentation=https://github.com/timescale/prometheus-postgresql-adapter Wants=network-online.target After=network-online.target [Service] Type=simple User=prometheus Group=prometheus ExecStart=/usr/local/bin/prometheus-postgresql-adapter-wrapper Restart=on-failure [Install] WantedBy=multi-user.target
which works fine (YMMV of course).
There may of course be a more elegant way of solving this issue, if so feel free to share.
Recently I had to work with some Python code which needs to be compatible with both the hopefully-soon-to-be-finally-deprecated Python 2.7 and recent 3.x versions.
String handling can be a tricky issue, particularly if the string in question needs to be cast to a Unicode object. Take the following example:
#!/usr/bin/env python
import ipaddress
addresses = list(ipaddress.ip_network(unicode('192.168.1.0/24')));
for address in addresses:
print(address)
This does of course fail in Python 3.x with an error like:
Traceback (most recent call last):
File "./python.py", line 5, in
addresses = list(ipaddress.ip_network(unicode('192.168.1.0/24')));
NameError: name 'unicode' is not defined
Remove the unicode() wrapper and it fails in Python 2.x with:
ipaddress.AddressValueError: '192.168.1.0/24' does not appear to be an IPv4 or IPv6 network. Did you pass in a bytes (str in Python 2) instead of a unicode object?
The solution is to use the "six" compatibility layer and add the following directive, which reassigns unicode() to a mutually compatible function:
#!/usr/bin/env python
import ipaddress
from six import u as unicode
addresses = list(ipaddress.ip_network(unicode('192.168.1.0/24')));
for address in addresses:
print(address)
Note that the "six" compatibility layer may need to be installed separately, in RedHat et al via the packages python2x-six and python3x-six respectively.
Spent a lot of time working out why openvpn wouldn't connect from a Vagrant virtual machine (running Ubuntu 14.04 LTS):
Tue Jan 10 02:51:25 2017 Control Channel Authentication: tls-auth using INLINE static key file
Tue Jan 10 02:51:25 2017 Outgoing Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication
Tue Jan 10 02:51:25 2017 Incoming Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication
Tue Jan 10 02:51:25 2017 Socket Buffers: R=[212992->200000] S=[212992->200000]
Tue Jan 10 02:51:25 2017 UDPv4 link local: [undef]
Tue Jan 10 02:51:25 2017 UDPv4 link remote: [AF_INET]xxx.xxx.xxx.xxx:1194
Tue Jan 10 02:51:25 2017 TLS: Initial packet from [AF_INET]xxx.xxx.xxx.xxx::1194, sid=92749f62 ced33a12
Tue Jan 10 02:52:25 2017 TLS Error: TLS key negotiation failed to occur within 60 seconds (check your network connectivity)
Tue Jan 10 02:52:25 2017 TLS Error: TLS handshake failed
Tue Jan 10 02:52:25 2017 SIGUSR1[soft,tls-error] received, process restarting
Tue Jan 10 02:52:25 2017 Restart pause, 2 second(s)
Turns out the openvpn version (2.3.2) is outdated; 2.3.4 or later is needed.
One annoyance when entering GPG passphrases in terminal applications on many systems is that a seperate GUI window pops up. To enable passphrase entry in the comfort of your own terminal, set the following line in .gnupg/gpg-agent.conf
pinentry-program /usr/bin/pinentry-ttyor in some older distributions (e.g. CentOS 7):
pinentry-program /usr/bin/pinentry-cursesThe running agent's settings can be reconfigured with:
gpg-connect-agent reloadagent /byeSee also "Making GPG pinentry work over SSH".
The OS X "top" command default output is somewhat hard to decipher (and modify interactively) compared to Linux. A simple workaround is to launch it with:
top -o cpu(or another field) which sorts on cpu activity rather than the PID (default).
htop is also available via MacPorts.
I was setting up a cronjob and it kept failing with the very unhelpful util.c: No such file or directory. After much headscratching it turns out this is a gnuplot error message, meaning it is unable to read from or write to a file (in this case the latter). The file in question is not of course util.c.