$ printf "val=%05d\n" 30 | tee hoge.txt val=00030 $ cat hoge.txt val=00030 |
"-a"オプションをつけると上書き禁止でもりもり文末にくっついていきます。
$ cat hoge.txt val=00030 $ printf "val=%05d\n" 99 | tee -a hoge.txt val=00099 $ cat hoge.txt val=00030 val=00099
逆に、一からやり直したい場合はオプションなしで。
$ cat hoge.txt val=00030 val=00099 $ printf "val=%05d\n" 100 | tee hoge.txt val=00100 $ cat hoge.txt val=00100
あらかじめ設定済みの/dev/ttyUSB0を対象とします。
$ tail -f /dev/ttyUSB0
または
$ cat /dev/ttyUSB0
一行書く。
$ echo "val=123" > /dev/ttyUSB0
改行不要なら"-n"で。
$ echo -n "val=123" > /dev/ttyUSB0
printfでもいけます。お好みで。
$ printf "val=%05d\n" 30 > /dev/ttyUSB0
XWindow環境(i3など)で"Fatal server error: could not open default font 'fixed'"と出たら……フォントの入れ忘れかもしれません。
環境を再構築していた時のこと……。
$ vncserver :1 -geometry 1280x800 -depth 24 Couldn't start Xtightvnc; trying default font path. Please set correct fontPath in the vncserver script. Couldn't start Xtightvnc process. 23/11/18 08:11:16 Xvnc version TightVNC-1.3.9 23/11/18 08:11:16 Copyright (C) 2000-2007 TightVNC Group 23/11/18 08:11:16 Copyright (C) 1999 AT&T Laboratories Cambridge 23/11/18 08:11:16 All Rights Reserved. 23/11/18 08:11:16 See http://www.tightvnc.com/ for information on TightVNC 23/11/18 08:11:16 Desktop name 'X' (linaro-alip:1) 23/11/18 08:11:16 Protocol versions supported: 3.3, 3.7, 3.8, 3.7t, 3.8t 23/11/18 08:11:16 Listening for VNC connections on TCP port 5901 Font directory '/usr/share/fonts/X11/misc/' not found - ignoring Font directory '/usr/share/fonts/X11/Type1/' not found - ignoring Font directory '/usr/share/fonts/X11/75dpi/' not found - ignoring Font directory '/usr/share/fonts/X11/100dpi/' not found - ignoring Fatal server error: could not open default font 'fixed' 23/11/18 08:11:17 Xvnc version TightVNC-1.3.9 23/11/18 08:11:17 Copyright (C) 2000-2007 TightVNC Group 23/11/18 08:11:17 Copyright (C) 1999 AT&T Laboratories Cambridge 23/11/18 08:11:17 All Rights Reserved. 23/11/18 08:11:17 See http://www.tightvnc.com/ for information on TightVNC 23/11/18 08:11:17 Desktop name 'X' (linaro-alip:1) 23/11/18 08:11:17 Protocol versions supported: 3.3, 3.7, 3.8, 3.7t, 3.8t 23/11/18 08:11:17 Listening for VNC connections on TCP port 5901 Font directory '/usr/share/fonts/X11/misc/' not found - ignoring Font directory '/usr/share/fonts/X11/Speedo/' not found - ignoring Font directory '/usr/share/fonts/X11/Type1/' not found - ignoring Font directory '/usr/share/fonts/X11/75dpi/' not found - ignoring Font directory '/usr/share/fonts/X11/100dpi/' not found - ignoring Fatal server error: could not open default font 'fixed'
エラーをみると、どうもフォント周りのようなので
$ sudo apt install xfonts-base Reading package lists... Done Building dependency tree Reading state information... Done The following additional packages will be installed: xfonts-encodings xfonts-utils The following NEW packages will be installed: xfonts-base xfonts-encodings xfonts-utils 0 upgraded, 3 newly installed, 0 to remove and 250 not upgraded. Need to get 6557 kB of archives. After this operation, 8380 kB of additional disk space will be used. Do you want to continue? [Y/n] y #... Setting up xfonts-utils (1:7.7+4) ... Setting up xfonts-base (1:1.0.4+nmu1) ...
これであらためてやると……はい動きました。
$ vncserver :1 -geometry 1280x800 -depth 24 New 'X' desktop is linaro-alip:1 Starting applications specified in /home/linaro/.vnc/xstartup Log file is /home/linaro/.vnc/linaro-alip:1.log
こういう事は構築に慣れた時ほど見落としがちです。
……なに、Docke? そんなハイカラなもん使えません（逆ギレ
scpコマンドをつかうと、UNIX系システム間ファイル送信できます。
たとえば、macOS上でセコセコ作っていたC++のコードをRasPiに転送したり……。
manの解説によると以下の通りなので……sshコマンドの仕組みを使ってるようです。
scp copies files between hosts on a network. It uses ssh(1) for data transfer, and uses the same authentication and provides the same security as ssh(1).
接続先が"pi@192.168.0.xxx"だとして……
今いるディレクトリのmain.py
$ scp ./main.py pi@192.168.0.xxx:~/www
$ scp -rC ./www pi@192.168.0.xxx:~/www
