Chapter 5 Answers to Exercises in Section 5.5
-
$ ls -la | cut -f 1 -d " " | sort -u | wc -l
-
$ date > listing; ls >>listing; mail ajlewis2 < listing
- Note: this will not work unless the mail program and an MTA like exim4 are installed and configured.
-
$ lsof -u myusername |grep /dev |less or $ lsof -u myUID |grep /dev |less -
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$ cat nonexistentfile 1> /var/tmp/output 2> /var/tmp/error $ less /var/tmp/output /var/tmp/output (END) $ less /var/tmp/error cat: nonexistentfile: No such file or directory
- Note that “/var/tmp/output (END)” is simply the end of the empty file.
-
$ file /sbin/ifconfig 1> /var/tmp/output 2> /var/tmp/error $ less /var/tmp/output /sbin/ifconfig: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), for GN U/Linux 2.6.0, dynamically linked (uses shared libs), for GNU/Linux 2.6.0, strip ped $ less /var/tmp/error /var/tmp/error (END)
grep root /etc/passwd /etc/nofiles > grepresults
output:/etc/passwd:root:x:0:0:root:/root:/bin/bash
error:grep: /etc/nofiles: No such file or directory/etc/init.d/sshd start 1> /var/tmp/output 2> /var/tmp/error
output: empty
error:bash: /etc/init.d/sshd: No such file or directory-
$ /etc/init.d/crond start > /var/tmp/output 2>&1 $ less /var/tmp/output bash: /etc/init.d/crond: No such file or directory $ /etc/init.d/crond start 1> /var/tmp/output 2> /var/tmp/error $ less /var/tmp/output /var/tmp/output (END) $ less /var/tmp/error bash: /etc/init.d/crond: No such file or directory
-
-
$ ps aux|grep myusername |wc -l 42
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ls -adF .* |grep -v / |wc -l
- List all, with directory entries, but not their contents and with the symbols. Do a reverse grep eliminating those with the directory symbol (/). Count the lines.
-
locate kernel | grep doc
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grep -r "root:x:0:0:root:/root:/bin/bash" /*
- Do this in a separate xterm–it will take a long time. Try it using only
/etc/*for faster results. (We know where this is.
) - Add “
2> /dev/null” on the end to avoid all the errors for lack of permission’'
- Do this in a separate xterm–it will take a long time. Try it using only
- I don’t find this one.
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> time; (creates empty file named "time". semicolon allows that more than one command per line.) date >> time; (runs command "date" and appends output to the empty "time" file) cat < time (looks at the "time" file which now has the date and time in it. -
grep "script-name-in-quotes" /etc/init.d/*
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