# Other ## Others ### **Describe the format and characteristics of image files.** ``` identify myimage.png #myimage.png PNG 1049x747 1049x747+0+0 8-bit sRGB 1.006MB 0.000u 0:00.000 ``` ### **Bash auto-complete (e.g. show options "now tomorrow never" when you press'tab' after typing "dothis")** [More examples](https://iridakos.com/tutorials/2018/03/01/bash-programmable-completion-tutorial.html) ``` complete -W "now tomorrow never" dothis # ~$ dothis # never now tomorrow # press 'tab' again to auto-complete after typing 'n' or 't' ``` ### **Displays a calendar** ``` # print the current month, today will be highlighted. cal # October 2019 # Su Mo Tu We Th Fr Sa # 1 2 3 4 5 # 6 7 8 9 10 11 12 # 13 14 15 16 17 18 19 # 20 21 22 23 24 25 26 # 27 28 29 30 31 # only display November cal -m 11 ``` ### **Convert the hexadecimal MD5 checksum value into its base64-encoded format.** ``` openssl md5 -binary /path/to/file| base64 # NWbeOpeQbtuY0ATWuUeumw== ``` ### **Forces applications to use the default language for output** ``` export LC_ALL=C # to revert: unset LC_ALL ``` ### **Encode strings as Base64 strings** ``` echo test|base64 #dGVzdAo= ``` ### **Get parent directory of current directory** ``` dirname `pwd` ``` ### **Read .gz file without extracting** ``` zmore filename # or zless filename ``` ### **Run command in background, output error file** ``` some_commands &>log & # or some_commands 2>log & # or some_commands 2>&1| tee logfile # or some_commands |& tee logfile # or some_commands 2>&1 >>outfile #0: standard input; 1: standard output; 2: standard error ``` ### **Run multiple commands in background** ``` # run sequentially (sleep 2; sleep 3) & # run parallelly sleep 2 & sleep 3 & ``` ### **Run process even when logout (immune to hangups, with output to a non-tty)** ``` # e.g. Run myscript.sh even when log out. nohup bash myscript.sh ``` ### **Send mail** ``` echo 'heres the content'| mail -a /path/to/attach_file.txt -s 'mail.subject' me@gmail.com # use -a flag to set send from (-a "From: some@mail.tld") ``` ### **Convert .xls to csv** ``` xls2csv filename ``` ### **Make BEEP sound** ``` speaker-test -t sine -f 1000 -l1 ``` ### **Set beep duration** ``` (speaker-test -t sine -f 1000) & pid=$!;sleep 0.1s;kill -9 $pid ``` ### **Editing your history** ``` history -w vi ~/.bash_history history -r #or history -d [line_number] ``` ### **Interacting with history** ``` # list 5 previous command (similar to `history |tail -n 5` but wont print the history command itself) fc -l -5 ``` ### **Delete current bash command** ``` Ctrl+U # or Ctrl+C # or Alt+Shift+# # to make it to history ``` ### **Add something to history (e.g. "addmetohistory")** ``` # addmetodistory # just add a "#" before~~ ``` ### **Get last history/record filename** ``` head !$ ``` ### **Clean screen** ``` clear # or simply Ctrl+l ``` ### **Backup with rsync** ``` rsync -av filename filename.bak rsync -av directory directory.bak rsync -av --ignore_existing directory/ directory.bak rsync -av --update directory directory.bak rsync -av directory user@ip_address:/path/to/directory.bak # skip files that are newer on receiver (i prefer this one!) ``` ### **Make all directories at one time!** ``` mkdir -p project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat} # -p: make parent directory # this will create project/doc/html/; project/doc/info; project/lib/ext ,etc ``` ### **Run command only if another command returns zero exit status (well done)** ``` cd tmp/ && tar xvf ~/a.tar ``` ### **Run command only if another command returns non-zero exit status (not finish)** ``` cd tmp/a/b/c ||mkdir -p tmp/a/b/c ``` ### **Use backslash "" to break long command** ``` cd tmp/a/b/c \ > || \ >mkdir -p tmp/a/b/c ``` ### **List file type of file (e.g. /tmp/)** ``` file /tmp/ # tmp/: directory ``` ### **Writing Bash script ('#!'' is called shebang )** ``` #!/bin/bash file=${1#*.} # remove string before a "." ``` ### **Python simple HTTP Server** ``` python -m SimpleHTTPServer # or when using python3: python3 -m http.server ``` ### **Read user input** ``` read input echo $input ``` ### **Array** ``` declare -a array=() # or declare array=() # or associative array declare -A array=() ``` ### **Send a directory** ``` scp -r directoryname user@ip:/path/to/send ``` ### **Fork bomb** ``` # Don't try this at home! # It is a function that calls itself twice every call until you run out of system resources. # A '# ' is added in front for safety reason, remove it when seriously you are testing it. # :(){:|:&};: ``` ### **Use the last argument** ``` !$ ``` ### **Check last exit code** ``` echo $? ``` ### **Extract .xz** ``` unxz filename.tar.xz # then tar -xf filename.tar ``` ### **Unzip tar.bz2 file (e.g. file.tar.bz2)** ``` tar xvfj file.tar.bz2 ``` ### **Unzip tar.xz file (e.g. file.tar.xz)** ``` unxz file.tar.xz tar xopf file.tar ``` ### **Extract to a path** ``` tar xvf -C /path/to/directory filename.gz ``` ### **Zip the content of a directory without including the directory itself** ``` # First cd to the directory, they run: zip -r -D ../myzipfile . # you will see the myzipfile.zip in the parent directory (cd ..) ``` ### **Output a y/n repeatedly until killed** ``` # 'y': yes # or 'n': yes n # or 'anything': yes anything # pipe yes to other command yes | rm -r large_directory ``` ### **Create large dummy file of certain size instantly (e.g. 10GiB)** ``` fallocate -l 10G 10Gigfile ``` ### **Create dummy file of certain size (e.g. 200mb)** ``` dd if=/dev/zero of=//dev/shm/200m bs=1024k count=200 # or dd if=/dev/zero of=//dev/shm/200m bs=1M count=200 # Standard output: # 200+0 records in # 200+0 records out # 209715200 bytes (210 MB) copied, 0.0955679 s, 2.2 GB/s ``` ### **Keep /repeatedly executing the same command (e.g Repeat 'wc -l filename' every 1 second)** ``` watch -n 1 wc -l filename ``` ### **Print commands and their arguments when execute (e.g. echo expr 10 + 20 )** ``` set -x; echo `expr 10 + 20 ` ``` ### **Print some meaningful sentences to you (install fortune first)** ``` fortune ``` ### **Colorful (and useful) version of top (install htop first)** ``` htop ``` ### **Press any key to continue** ``` read -rsp $'Press any key to continue...\n' -n1 key ``` ### **Run sql-like command on files from terminal** ``` # download: # https://github.com/harelba/q # example: q -d "," "select c3,c4,c5 from /path/to/file.txt where c3='foo' and c5='boo'" ``` ### **Using Screen for multiple terminal sessions** ``` # Create session and attach: screen # Create a screen and name it 'test' screen -S test # Create detached session foo: screen -S foo -d -m # Detached session foo: screen: ^a^d # List sessions: screen -ls # Attach last session: screen -r # Attach to session foo: screen -r foo # Kill session foo: screen -r foo -X quit # Scroll: # Hit your screen prefix combination (C-a / control+A), then hit Escape. # Move up/down with the arrow keys (↑ and ↓). # Redirect output of an already running process in Screen: # (C-a / control+A), then hit 'H' # Store screen output for Screen: # Ctrl+A, Shift+H # You will then find a screen.log file under current directory. ``` ### **Using Tmux for multiple terminal sessions** ``` # Create session and attach: tmux # Attach to session foo: tmux attach -t foo # Detached session foo: ^bd # List sessions: tmux ls # Attach last session: tmux attach # Kill session foo: tmux kill-session -t foo # Create detached session foo: tmux new -s foo -d # Send command to all panes in tmux: Ctrl-B :setw synchronize-panes # Some tmux pane control commands: Ctrl-B # Panes (splits), Press Ctrl+B, then input the following symbol: # % horizontal split # " vertical split # o swap panes # q show pane numbers # x kill pane # space - toggle between layouts # Distribute Vertically (rows): select-layout even-vertical # or Ctrl+b, Alt+2 # Distribute horizontally (columns): select-layout even-horizontal # or Ctrl+b, Alt+1 # Scroll Ctrl-b then \[ then you can use your normal navigation keys to scroll around. Press q to quit scroll mode. ``` ### **Pass password to ssh** ``` sshpass -p mypassword ssh root@10.102.14.88 "df -h" ``` ### **Wait for a pid (job) to complete** ``` wait %1 # or wait $PID wait ${!} #wait ${!} to wait till the last background process ($! is the PID of the last background process) ``` ### **Convert pdf to txt** ``` sudo apt-get install poppler-utils pdftotext example.pdf example.txt ``` ### **List only directory** ``` ls -d */ ``` ### **List one file per line.** ``` ls -1 # or list all, do not ignore entries starting with . ls -1a ``` ### **Capture/record/save terminal output (capture everything you type and output)** ``` script output.txt # start using terminal # to logout the screen session (stop saving the contents), type exit. ``` ### **List contents of directories in a tree-like format.** ``` tree # go to the directory you want to list, and type tree (sudo apt-get install tree) # output: # home/ # └── project # ├── 1 # ├── 2 # ├── 3 # ├── 4 # └── 5 # # set level directories deep (e.g. level 1) tree -L 1 # home/ # └── project ``` ### **Set up virtualenv(sandbox) for python** ``` # 1. install virtualenv. sudo apt-get install virtualenv # 2. Create a directory (name it .venv or whatever name your want) for your new shiny isolated environment. virtualenv .venv # 3. source virtual bin source .venv/bin/activate # 4. you can check check if you are now inside a sandbox. type pip # 5. Now you can install your pip package, here requirements.txt is simply a txt file containing all the packages you want. (e.g tornado==4.5.3). pip install -r requirements.txt ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://alomancy.gitbook.io/guides/cheat-sheets/bash-cheat-sheets/other.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. 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