diff options
| -rw-r--r-- | bash.html.markdown | 69 |
1 files changed, 68 insertions, 1 deletions
diff --git a/bash.html.markdown b/bash.html.markdown index a62bd167..b1a14bdb 100644 --- a/bash.html.markdown +++ b/bash.html.markdown @@ -11,7 +11,10 @@ contributors: - ["Rahil Momin", "https://github.com/iamrahil"] - ["Gregrory Kielian", "https://github.com/gskielian"] - ["Etan Reisner", "https://github.com/deryni"] - - ["Jonathan Wang", "https://github.com/Jonathansw" ] + - ["Jonathan Wang", "https://github.com/Jonathansw"] + - ["Leo Rudberg", "https://github.com/LOZORD"] + - ["Betsy Lorton", "https://github.com/schbetsy"] + - ["John Detter", "https://github.com/jdetter"] filename: LearnBash.sh --- @@ -20,6 +23,8 @@ Nearly all examples below can be a part of a shell script or executed directly i [Read more here.](http://www.gnu.org/software/bash/manual/bashref.html) +Another recommened link: [The Command Line Crash Course](http://cli.learncodethehardway.org/book/) + ```bash #!/bin/bash # First line of the script is shebang which tells the system how to execute @@ -90,6 +95,21 @@ echo "Number of arguments passed to script: $#" echo "All arguments passed to script: $@" echo "Script's arguments separated into different variables: $1 $2..." +# Now that we know how to echo and use variables, +# let's learn some of the other basics of bash! + +# Getting our current directory is available through the command `pwd`. +# `pwd` stands for "print working directory". +# We can also use the builtin variable `$PWD`. +# Observer that the following are equivalent: +echo "I'm in $(pwd)" # execs `pwd` and interpolates output +echo "I'm in $PWD" # interpolates the variable + +# If you get too much output in your terminal, or from a script, the command +# `clear` clears your screen +clear +# Ctrl-L also works for clearing output + # Reading a value from input: echo "What's your name?" read Name # Note that we didn't need to declare a new variable @@ -138,12 +158,37 @@ ls # These commands have options that control their execution: ls -l # Lists every file and directory on a separate line +ls -t # Sort the directory contents by last-modified date (descending) +ls -R # Recursively `ls` this directory and all of its subdirectories # Results of the previous command can be passed to the next command as input. # grep command filters the input with provided patterns. That's how we can list # .txt files in the current directory: ls -l | grep "\.txt" +# Use `cat` to print files to stdout: +cat file.txt + +# We can also read the file using `cat`: +Contents=$(cat file.txt) +echo "START OF FILE\n$Contents\nEND OF FILE" + +# Use `cp` to copy files or directories from one place to another. +# `cp` creates NEW versions of the sources, +# so editing the copy won't affect the original (and vice versa). +# Note that it will overwrite the destination if it already exists. +cp srcFile.txt clone.txt +cp -r srcDirectory/ dst/ # recursively copy + +# Look into `scp` or `sftp` if you plan on exchanging files between computers. +# `scp` behaves very similarly to `cp`. +# `sftp` is more interactive. + +# Use `mv` to move files or directories from one place to another. +# `mv` is similar to `cp`, but it deletes the source. +# `mv` is also useful for renaming files! +mv s0urc3.txt dst.txt # sorry, l33t hackers... + # Since bash works in the context of a current directory, you might want to # run your command in some other directory. We have cd for changing location: cd ~ # change to home directory @@ -152,6 +197,14 @@ cd .. # go up one directory cd /home/username/Documents # change to specified directory cd ~/Documents/.. # still in home directory..isn't it?? +# Use subshells to work across directories +(echo "First, I'm here: $PWD") && (cd someDir; echo "Then, I'm here: $PWD") +pwd # still in first directory + +# Use `mkdir` to create new directories. +mkdir myNewDir +# The `-p` flag causes new intermediate directories to be created as necessary. +mkdir -p myNewDir/with/intermediate/directories # You can redirect command input and output (stdin, stdout, and stderr). # Read from stdin until ^EOF$ and overwrite hello.py with the lines @@ -191,7 +244,9 @@ echo "#helloworld" | cat > output.out echo "#helloworld" | tee output.out >/dev/null # Cleanup temporary files verbosely (add '-i' for interactive) +# WARNING: `rm` commands cannot be undone rm -v output.out error.err output-and-error.log +rm -r tempDir/ # recursively delete # Commands can be substituted within other commands using $( ): # The following command displays the number of files and directories in the @@ -282,6 +337,13 @@ sed -i 's/okay/great/g' file.txt grep "^foo.*bar$" file.txt # pass the option "-c" to instead print the number of lines matching the regex grep -c "^foo.*bar$" file.txt +# Other useful options are: +grep -r "^foo.*bar$" someDir/ # recursively `grep` +grep -n "^foo.*bar$" file.txt # give line numbers +grep -rI "^foo.*bar$" someDir/ # recursively `grep`, but ignore binary files +# perform the same initial search, but filter out the lines containing "baz" +grep "^foo.*bar$" file.txt | grep -v "baz" + # if you literally want to search for the string, # and not the regex, use fgrep (or grep -F) fgrep "foobar" file.txt @@ -290,6 +352,11 @@ fgrep "foobar" file.txt # Here trap command will execute rm if any one of the three listed signals is received. trap "rm $TEMP_FILE; exit" SIGHUP SIGINT SIGTERM +# `sudo` is used to perform commands as the superuser +$NAME1=$(whoami) +$NAME2=$(sudo whoami) +echo "Was $NAME1, then became more powerful $NAME2" + # Read Bash shell builtins documentation with the bash 'help' builtin: help help help |