\nWhen a program is executed, it has access to three special files: ____ (1),\n____ (2), and ____ (3). The first is connected to the keyboard, while the second\nand third are attached to the screen or terminal.\n
\n\nTo redirect the contents of a file into a command such as\nmd5sum, we can do:
\n$ md5sum ____ file # (4)\n\n\n
To redirect the output of a command such as date to a file, we\ncan do:
\n$ date ____ file # (5)\n\n\n
To append the output of a command such as uname to a file, we\ncan do:
\n$ uname -a ____ file # (6)\n\n\n
To redirect only the error messages of a command such as find\nto a file, we can do:
\n$ find /etc ____ file # (7)\n\n\n
To redirect both the output and error messages of a command such as\ndu, we can do:
\n$ du /etc ____ file # (8)\n\n\n
To redirect the output of a command such as ls to the input of\nanother command such as grep, we can do:
\n$ ls /etc ____ grep host # (9)\n\n" }, "q02": { "type": "single", "question": "\n
Are the following two pipelines equivalent?
\n\n\n$ du -h /etc 2> /dev/null | sort -h > output.txt\n\n\n
\n$ du -h /etc | sort -h > output.txt 2> /dev/null\n\n", "responses": { "true": "Yes, the pipelines have the same behavior and produce the same output.", "no_store": "No, the first pipeline redirects the output of
du to a file and then sorts the file, while the second pipeline pipes the output of du into sort and then stores it into two files.",
"no_error": "No, the first pipeline discards the error messages of the du, while the second pipeline discards the error messages of sort.",
"no_output": "No, the first pipeline discards the output of du before sorting, while the second pipeline discards the output of the whole pipeline."
}
},
"q03": {
"type": "multiple",
"question": "\nTwo useful features in a typical Unix shell are pathname expansion and\nbrace expansion. Given the following output of ls:
\n2002-01 2002-07 2003-01 2003-07 2004-01 2004-07 2005-01 2005-07 2006-01 2006-07\n2002-02 2002-08 2003-02 2003-08 2004-02 2004-08 2005-02 2005-08 2006-02 2006-08\n2002-03 2002-09 2003-03 2003-09 2004-03 2004-09 2005-03 2005-09 2006-03 2006-09\n2002-04 2002-10 2003-04 2003-10 2004-04 2004-10 2005-04 2005-10 2006-04 2006-10\n2002-05 2002-11 2003-05 2003-11 2004-05 2004-11 2005-05 2005-11 2006-05 2006-11\n2002-06 2002-12 2003-06 2003-12 2004-06 2004-12 2005-06 2005-12 2006-06 2006-12\n\n\n
Note: All file names are in the format YEAR-MONTH.
Using bash's expansion syntax, complete the following prompts.
To list all the files from 2002, we could use the following expressions\n(select all that work correctly):
\n\n\n$ ls ____\n2002-01 2002-02 2002-03 2002-04 2002-05 2002-06 2002-07 2002-08 2002-09 2002-10 2002-11 2002-12\n\n", "responses": { "a": "2002", "b": "2002-*", "c": "2002-{01..12}", "d": "2*2*" } }, "q04": { "type": "multiple", "question": "\n
Continuing from question 03, to list all the files from the month of\nDecember, we could do:
\n\n\n$ ls ____\n2002-12 2003-12 2004-12 2005-12 2006-12\n\n", "responses": { "a": "*-12", "b": "*[12]", "c": "????-12", "d": "{2002..2006}-12" } }, "q05": { "type": "multiple", "question": "\n
Continuing from question 03, to list all the files from the month of\nJanuary to June, we could do:
\n\n\n$ ls ____ # (3)\n2002-01 2002-04 2003-01 2003-04 2004-01 2004-04 2005-01 2005-04 2006-01 2006-04\n2002-02 2002-05 2003-02 2003-05 2004-02 2004-05 2005-02 2005-05 2006-02 2006-05\n2002-03 2002-06 2003-03 2003-06 2004-03 2004-06 2005-03 2005-06 2006-03 2006-06\n\n", "responses": { "a": "*-0[1-6]", "b": "*-{01..06}", "c": "*0[123456]", "d": "2?2[0]{1..6}" } }, "q06": { "type": "blank", "question": "\n
Two other important features of a typical Unix shell are variables (ie.\nparameter expansion) and command substitution. Using these features,\ncomplete the following prompts:
\n\nTo print all the environment variables in the shell, we could do:
\n\n\n$ ____ # (1)\n\n\n
To print the value of the HOME variable, we could do:
\n$ echo ____ # (2)\n\n\n
To set the value of the SHELL variable to\n/bin/bash, we could do:
\n$ ____ # (3)\n\n\n
To compute the md5sum of the ls command\nwhile also looking up its location, we could do:
\n$ md5sum ____ # (4)\n\n" }, "q07": { "type": "multiple", "question": "\n
Given the following output of ls -l:
\n-rw------- 1 pbui notre-dame 0 Jan 18 07:19 Beastie\n-rwxr-xr-x 1 pbui notre-dame 0 Jan 18 07:18 Huxley\n-rwxr-x--- 1 pbui notre-dame 0 Jan 18 07:18 Tux\n\n\n
Which files are executable by the owner?
\n", "responses": { "beastie": "Beastie", "huxley": "Huxley", "tux": "Tux" } }, "q08": { "type": "multiple", "question": "\nGiven the directory listing in question 07, which files are readable by\nmembers of the notre-dame group?
Given the directory listing in question 07, which files are not writable\nby the world?
\n", "responses": { "beastie": "Beastie", "huxley": "Huxley", "tux": "Tux" } }, "q10": { "type": "blank", "question": "\nGiven the directory listing in question 07:
\n\nBeastie's permissions? ____Huxley's permissions? ____Tux's permissions? ____Suppose you run the bc command\n\n
bc process was still running, we could terminate\nthe process using the keystroke: CTRL-____.bc process was still running, and we knew its PID,\nwe could terminate the process using the command: ____ PID.bc process was still running, and we did not know\nits PID, we could terminate the process using the command: ____ bc.