Library Carpentry: The UNIX Shell: Reference

Key Points

Shell Cheat Sheet

Shell: Basics

pwd - print working directory

man - display the user manual

history - displays the history list with line numbers, use n to limit the list

ls - list contents of a directory

• ls -l - list file information
• ls -lh - list human readable file information
• ls -F - list files and directories (directories will have a trailing /)
• ls -a - list all files, including hidden files
• ls *.txt - list all files that end with .txt

cd change directory

cd pathname - takes you to the directory specified by pathname

cd ~ - takes you to your home directory

cd .. - takes you up one directory

Shell: Interacting with Files

mkdir make a directory

cat print to shell or send file or files to output

head output first 10 lines of a file or files

tail output last 10 lines of a file or files

mv rename or move a file or files. Syntax for renaming a file: mv FILENAME NEWFILENAME

cp make a backup copy of a file or files. Syntax: cp FILENAME NEWFILENAME

> redirect output. Syntax with cat: cat FILENAME1 FILENAME2 > NEWFILENAME

>> redirect output by appending to the filename specified. Syntax with cat: cat FILENAME1 FILENAME2 >> NEWFILENAME

rm remove a file or files. NB: USE WITH EXTREME CAUTION!!!

rmdir -r will delete a directory, even if it is not empty.

rmdir -r-i will delete a directory, even if it is not empty, but will ask you to confirm each deletion.

touch will update timestamp information on files. __

Shell: Wildcards

? a placeholder for one character or number

* a placeholder for zero or more characters or numbers

[] defines a class of characters

Examples

• foobar?: matches 7-character strings starting with foobar and ending with one character or number
• foobar*: matches strings that start with foobar and end with zero or more other characters or numbers
• foobar*txt: matches strings that start with foobar and end with txt
• [1-9]foobar?: matches 8-character strings that start that start with a number, have foobar after the number, and end with any character or number.

Shell: Counting and Mining

wc word count

• -w: count words
• -l: count lines
• -c: count characters

sort sort input

grep global regular expression print

• -c: displays counts of matches for each file
• -i: match with case insensitivity
• -w: match whole words
• -v: exclude match
• --file=FILENAME.txt: use the file FILENAME.txt as the source of strings used in query
• |: (vertical bar character) send output from one command into another command

Shell: Working with Free Text

sed is used to modify files, use -e flag to run multiple commands

tr translates or deletes characters in a file

• [:punct:]: punctuation characters
• [:upper:]: upper-case characters
• [:lower:]: lower-case alphabetic characters

'''\n translates every blank space into \n, then renders on a new line

uniq reports or filters repeated lines in a file, use with -c to do a word count of the duplicates