Terminal Commands

This page summarises common terminal commands that span across categories.

Note that a lot of terminal shortcuts are stored at /usr/local/beg, e.g. pip3.

The file .bashrc contains the aliases for commands.

Commands

General

  • sudo -i Goes into super-administrator mode. exit To exit this admin mode.

  • cat Takes a file and prints it to screen.

  • <command> | pbcopy

    • This copies the output of command to the clipboard. pbpaste will paste the contents of the clipboard.
    • -pboard {board} as an argument allows you to use different pasteboards, but I have, as yet, been unable to figure out quite how this works.

  • The | creates pipelines. This means that the output from the first command is connected to the input of the next command.

File Management

  • ls -altr

    • -a - Shows hidden files, i.e. those that start with a .
    • -l - Provides extra information
    • -t - Lists them in date order
    • -r - Lists them with the most recent at the bottom

  • brew cask uninstall <app_name>

  • brew cask search <app_name>

Running Processes

  • ps Lists the currently running processes on the computer.
    • -e is the same as -A and displays information about other users' processes, including those without controlling terminals.
    • -f displays the bid, pid, and other information about the processes.
    • For example ps -ef | grep java returns a list of all the running processes that are using java.

Web

  • curl -L <web_page>
    • curl is a tool to transfer data from or to a server, using one of the supported protocols.
    • The -L argument: If the server reports that the requested page has moved to a different location (indicated with a Location: header and a 3XX response code), this option will make curl redo the request on the new place.

Variables:

  • ${} Whatever is run inside the parentheses is run inside a subshell and is returned as a value. It can be used in a string to add the returned string within a larger string e.g. echo "http://${nodeip}"

    • $<variable-name> Can be used within a string to add a variable to the string.
    • To print a variable on mac use echo $HOME, whilst on windows use echo %PATH% (having set it with set PATH=).
    • <variable_name>=$(<command_that_returns_value>) This how to set a variable in CLI.

  • cat /dev/urandom | env LC_CTYPE=C tr -dc 'a-zA-Z0-9' | fold -w 256 | head -n 1 | xargs echo -n This generates a 2048-buit secret key. The LC_CTYPE+C command selects the “C” locale, which basically means means “nothing fancy”.

  • env

    • This is the 'set environment and execute command, or print environment' method.

  • env prints all env variables VCAP_SERVICES environment variables

Path and File Access

  • ln -s "/Applications/Sublime Text 3.app/Contents/SharedSupport/bin/subl" /usr/local/bin/subl Basically you have to put the executable for the app on the path, which you achieve by putting in one of the /usr/local/ things which are themselves on the path.

  • `export PATH=$PATH:<~/path>`` Add a new directory to PATH

  • ln -s <executable> <new_location> Link a file to something; -s created a symbollic link (doesn't mve anything) (sometimes have to save in .) For example, to create a symbolic link to open Sublime Text, use the following command:

  • To remove a path from the PATH environment variable on a mac:

echo $PATH // and copy it's value
export PATH=""
export PATH="/path/you/want/to/keep"

Or to add a path to the PATH environment variable:

// export PATH=/opt/apache-maven-3.5.3/bin:$PATH
export PATH=/path/want/to/add:$PATH

Repackaging Files

When tar has been used to collect many files into one archive file, it is referred to as a tarball.

  • tar -cvzf <name of tarball>.tgz /path/to/source/folder

This uses tar to archive the directory and then gzip to compress it. The arguments are as follows: compress, zip, verbose and file.

  • -x, --extract, --get

        extract files from an archive

  • -v, --verbose

        verbosely list files processed

  • -z, --gzip, --gunzip, --ungzip

        filter the archive through gzimkdir up

  • -f, --file [HOSTNAME:]F

        use archive file or device F (default "-", meaning stdin/stdout)

  • -C <new_directory_name>

    In x mode this changes the directories after opening the archive but before extracting entries from the archive. In c and r mode this changes the directory before adding the following files.

  • -t : List archive contents to stdout. Prints the absolute path of all the files in the archive.

  • tar -xvzf /path/to/yourfile.tgz - Extract tgz

  • unzip <zip_file> -d <relative_path> The directory in which to extract the files.

    zip -r squash.zip dir1: zips a directory

GNU tar
brew install gnu-tar            // This installs GNU tar, which packages files differently.

gtar <>

  • -c : Create a new archive. Directories are archived recursively, unless the --no-recursion argument is used.

  • -f : Read the archive from from a specified file

  • -z :

  • tar -cvf files.tar /path/to/file0 /path/to/file1 ; gzip -9 files.tar This first TARs the file and then gzips it. .Z file type is an old Unix/ Linux compression type, achieved with the $compress command.

pax

This is for reading and writing file archives and copying directory hierarchies

Permissions

  • The different permission are as follows:

    • r = read access
    • w = write access
    • x = execute
    • d = indicates a directory
    • l = symbolic link
    • @ = indicates that this file has extended attributes

  • chmod chmod [options] [permissions] [file] [name] Used to change the permissions of files or directories. It stands for 'change mode'.

  • ls -l This displays (from left to right) the owner's permissions, the group permissions and everybody's permissions.

  • sudo chmod 777 <filepath> This gives access to everyone, but is bad practice.;

Bash

  • source ./.bashrc

This reloads the bashrc file so that you don't have to close vim and terminal, and hence Eclipse.

Publish an i2 component

mkdir publish

mv macos*tar.gz publish

components publish "External/IBM JDK 8 Darwin Binary Distribution:8.0.5.5" /copy_to_repository /export_fs:$PWD/publish /retraction:deprecate /retract_at:+6m

Searching within Terminal

  • find . name <search_term> | grep <search_term> This searches for a search term within the name of the all the files in the current directory and lower.

  • grep [OPTIONS] PATTERN [FILE...] grep which stands for global regular expression print, processes text line by line and prints any lines which match a specified pattern.

  • `which `` This locates a file on the path.

  • <command> $PATH Lists all the places terminal has looked for the command which where is the program installed

  • ls -l | grep <search term>

iTerm

  • cmmd + option + / Gives a drop down of the most commonly used terminals.

  • cmmd + D Splits the current tab into two panes vertically.

  • cmmd + shift + D Splits the current tab into two panes horizontally

  • ctrl + cmmd + arrows Resize the split panes

  • cmmd + option + arrows Jumps between split panes

  • cmmd Whilst holding the command button, one can select many continuous selections.

File manipulation and inspection

  • sed 's/FindThisWord/ReplaceWithThisWord/g' file.txt You can replace all the instances of a word in a file with the use of this command.

  • fold [-bs] [-w width] [file ...] This is a filter that folds the contents of the specified files, breaking the lines to have a maximum of 80 columns.

  • jar tf <jar_name> Displays the contents of a jar.

Other

  • stdout seems to be a holder for the standard location to put output, but I do not know any more than this. Apparently opening the file /dev/stdout is equivalent to the following call: fd = fcntl(STDOUT_FILENO, F_DUPFD, 0)

  • xargs [command [initial-arguments]] xargs builds and executes command lines from standard input. It reads items from the standard input, delimited by blanks (which can be protected with double or single quotes or a backslash) or newlines, and executes the command (the default command is echo, located at /bin/echo) one or more times with any initial-arguments followed by items read from standard input. Blank lines on the standard input are ignored.

  • head [-#] Prints out the first # of lines of the stated file.

  • rm -Rf This deletes all the contents of a directory without having to type yes to each sub-directory.

    find . \! -name 'file' -delete

    This deletes all files apart from the one specified.

    • tr [-Ccsu] string1 string2

    This utility copies the standard input to the standartd output, substituting or deleting selected characters.

  • cat [-benstuv] [file ...]

    The cat utility reads files sequentially, writing them to the standard output.

  • open
    • -e Opens the file with TextEdit.

Shortkeys

  • cmmd + down

Opens a the highlighted file in Finder.

  • cmmd + up

Traverses to the above direcory in Finder.

Other

  • On a windows the command to move a file is not mv but move

shebang

e.g. #!/bin/sh is an example of a shebang, which tells the parent shell which interpreter should be used to execute the script.

Redirection

> is for redirecting an output file-descriptor and > is for redirecting an input file-descriptor. What this means is that the output of a command can be written to a file with the command ls -l > output.txt.

Synchronising files

rsync: see common usages here.

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