1 files changed, 99 insertions, 10 deletions
diff --git a/bash.html.markdown b/bash.html.markdown
index 845ebead..3b163638 100644
--- a/bash.html.markdown
+++ b/bash.html.markdown
@@ -8,6 +8,8 @@ contributors:
     - ["Denis Arh", "https://github.com/darh"]
     - ["akirahirose", "https://twitter.com/akirahirose"]
     - ["Anton Strömkvist", "http://lutic.org/"]
+    - ["Rahil Momin", "https://github.com/iamrahil"]
+    - ["Gregrory Kielian", "https://github.com/gskielian"]
 filename: LearnBash.sh
 ---
 
@@ -73,9 +75,9 @@ echo Hello, $NAME!
 # use 'man test' for more info about conditionals
 if [ $NAME -ne $USER ]
 then
-    echo "Your name is your username"
-else
     echo "Your name isn't your username"
+else
+    echo "Your name is your username"
 fi
 
 # There is also conditional execution
@@ -109,12 +111,45 @@ ls -l # Lists every file and directory on a separate line
 # .txt files in the current directory:
 ls -l | grep "\.txt"
 
-# You can also redirect a command, input and error output.
-python2 hello.py < "input.in"
-python2 hello.py > "output.out"
-python2 hello.py 2> "error.err"
-# The output error will overwrite the file if it exists, if you want to
-# concatenate them, use ">>" instead.
+# You can redirect command input and output (stdin, stdout, and stderr).
+# Read from stdin until ^EOF$ and overwrite hello.py with the lines
+# between "EOF":
+cat > hello.py << EOF
+#!/usr/bin/env python
+from __future__ import print_function
+import sys
+print("#stdout", file=sys.stdout)
+print("#stderr", file=sys.stderr)
+for line in sys.stdin:
+    print(line, file=sys.stdout)
+EOF
+
+# Run hello.py with various stdin, stdout, and stderr redirections:
+python hello.py < "input.in"
+python hello.py > "output.out"
+python hello.py 2> "error.err"
+python hello.py > "output-and-error.log" 2>&1
+python hello.py > /dev/null 2>&1
+# The output error will overwrite the file if it exists,
+# if you want to append instead, use ">>":
+python hello.py >> "output.out" 2>> "error.err"
+
+# Overwrite output.txt, append to error.err, and count lines:
+info bash 'Basic Shell Features' 'Redirections' > output.out 2>> error.err
+wc -l output.out error.err
+
+# Run a command and print its file descriptor (e.g. /dev/fd/123)
+# see: man fd
+echo <(echo "#helloworld")
+
+# Overwrite output.txt with "#helloworld":
+cat > output.out <(echo "#helloworld")
+echo "#helloworld" > output.out
+echo "#helloworld" | cat > output.out
+echo "#helloworld" | tee output.out >/dev/null
+
+# Cleanup temporary files verbosely (add '-i' for interactive)
+rm -v output.out error.err output-and-error.log
 
 # Commands can be substituted within other commands using $( ):
 # The following command displays the number of files and directories in the
@@ -134,14 +169,34 @@ case "$VARIABLE" in
 esac
 
 # for loops iterate for as many arguments given:
-# The contents of var $VARIABLE is printed three times.
+# The contents of $VARIABLE is printed three times.
 for VARIABLE in {1..3}
 do
     echo "$VARIABLE"
 done
 
+# Or write it the "traditional for loop" way:
+for ((a=1; a <= 3; a++))
+do
+    echo $a
+done
+
+# They can also be used to act on files..
+# This will run the command 'cat' on file1 and file2
+for VARIABLE in file1 file2
+do
+    cat "$VARIABLE"
+done
+
+# ..or the output from a command
+# This will cat the output from ls.
+for OUTPUT in $(ls)
+do
+    cat "$OUTPUT"
+done
+
 # while loop:
-while [true]
+while [ true ]
 do
     echo "loop body here..."
     break
@@ -178,4 +233,38 @@ sort file.txt
 uniq -d file.txt
 # prints only the first column before the ',' character
 cut -d ',' -f 1 file.txt
+# replaces every occurrence of 'okay' with 'great' in file.txt, (regex compatible)
+sed -i 's/okay/great/g' file.txt
+# print to stdout all lines of file.txt which match some regex, the example prints lines which begin with "foo" and end in "bar"
+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
+# if you literally want to search for the string, and not the regex, use fgrep (or grep -F)
+fgrep "^foo.*bar$" file.txt 
+
+
+# Read Bash shell builtins documentation with the bash 'help' builtin:
+help
+help help
+help for
+help return
+help source
+help .
+
+# Read Bash manpage documentation with man
+apropos bash
+man 1 bash
+man bash
+
+# Read info documentation with info (? for help)
+apropos info | grep '^info.*('
+man info
+info info
+info 5 info
+
+# Read bash info documentation:
+info bash
+info bash 'Bash Features'
+info bash 6
+info --apropos bash
 ```