“屁股决定脑袋”这句话真是好悲伤啊。许多人连自己屁股在哪里都搞不清楚。
#!/bin/bash max_jobs=${JOBS:=$(nproc)} pipe_file=$(mktemp --dry-run) mkfifo ${pipe_file} exec {pipe_fd}<>${pipe_file} rm ${pipe_file} printf "%-${max_jobs}s" >&${pipe_fd} for job in ... do read -n 1 -u ${pipe_fd} ( echo "start ${job}" # do stuff for ${job} ... echo "finish ${file}" printf '%-1s' >&${pipe_fd} )& done wait
This piece of script uses a FIFO to manage the parallel jobs. Initially, the FIFO is filled with n characters, each representing an available slot for a job. Before a job starts, it reads a character from the FIFO. Once a job finishes, a character is written back to the FIFO. Thus the FIFO is empty if and only if there are n jobs running. New jobs will not be spawned because the FIFO read will block until at least 1 running job finishes.
{varname} style automatic file descriptor allocation requires bash 4.1+.
Reference:
https://superuser.com/questions/184307/bash-create-anonymous-fifo
There are problems in the rt2800usb driver on Linux and according to this post I have to set nohwcrypt=1 for the rt2800usb kernel module.
sudo ifconfig wlan0 down sudo rmmod -f rt2800usb sudo modprobe rt2800usb nohwcrypt=1 sudo ifconfig wlan0 up
To make it permenant I have to put the following in /etc/modprobe.d/rt2800usb.conf
options rt2800usb nohwcrypt=1
Damn it… I really should have found this earlier…
记得初中的时候经常有作文题讲，人生是两杯酒，一杯苦酒，一杯甜酒，以此教育大家先苦后甜。
然而，任何智力正常的人，不都应该把甜酒喝了吧苦酒倒了吗 (╯￣Д ￣)づ╧═╧
今天洗澡的时候，突然想到，这个事情其实可以更严谨一点建模：
人类出生的时候有两杯酒，一杯苦酒，一杯甜酒。规定酒必须一杯一杯喝。如果喝掉苦酒，则会再端上来一杯苦酒和一杯甜酒；如果喝掉甜酒，则自动有一杯苦酒被倒掉。酒不允许超支和借贷，也不会随意消失或出现。人类喜欢喝甜酒，不喜欢喝苦酒。
于是想喝甜酒就必须先喝苦酒，要是图一时之快喝光了甜酒就不再有机会喝到更多的甜酒，因为喝苦酒是唯一获得更多甜酒的方式。所以还是乖乖地先苦后甜吧。
然而，都说了是反鸡汤，因为事实上——
有的人出生的时候是带了一箱甜酒啊 (╯￣Д ￣)づ╧═╧
有的人出生的时候是带了一箱苦酒，而且喝前面一大半的时候还不给带甜酒 (╯￣Д ￣)づ╧═╧
有的人好死不死就是会被天上掉下来的甜酒砸啊 (╯￣Д ￣)づ╧═╧
不说了，我去喝苦酒去了 *~(￣▽￣)~[]
If you are working with some software which requires you to source some code and messes up with your PATH and other environment variables like Vivado and Merlin compiler, here is a simple and straightforward method to get rid of the mess (to some extent).
#!/bin/bash VERSION=2016.1 . /space/Xilinx/SDAccel/${VERSION}/settings64.sh # do something if necessary if ! test "$0" -ef "$(which $(basename $0))" then exec $(basename $0) "$@" else if test -t 2 then echo "Recursive call detected!" 1&>2 fi fi
Some notes:
#!/bin/bash if you or your script use bash-specific syntax!chmod +x!. instead of source, which improves compatibility!
On Linux, if you see
mtr: unable to get raw sockets.
The following might help:
sudo chmod 4755 $(which mtr)
The reason this happens is that only privileged processes (or processes with proper capabilities(7) on Linux) can create raw sockets, which is needed to send/receive ICMP packets. By chmod(2), the executable will get the S_ISUID mode, which means it can set process effective user ID when execve(2).
A safer solution is
sudo setcap cap_net_raw+ep $(which mtr)
which only gives mtr the cap_net_raw capability.
Reinstalling the mtr package via the package manager should also solve the problem since it will do whatever appropriate to make it work.
According to cplusplus.com, std::vector<bool> in C++ is specialized and consumes only 1/8 space as you may have expected. However, as 8-bit bytes are usually the shortest available type in most implementations, thread-safety is not guaranteed. This could have caused significant trouble in my current project. How lucky I am to notice this interesting feature before I have actually encountered trouble.
Besides, std::bitset provides a fixed size bit array whose length is fixed at compile-time.
今天看到一句话，“不理解，但尊重”。且不说社会，就是放在一个人身上，又有谁能说到做到呢。
世间事，总有一些，我可以不反对，但绝不会赞同。
突然有一天，我的iPad播不出声音了……耳机不行……扬声器也不行……蓝牙都不行……不是静音的问题……重启没有用……所有的播放器都没声了……直到我找到了这篇帖子。其实只要删除
/System/Library/PrivateFrameworks/IAP.framework/Support/iapd
然后重启就行了……