Linux Shell 基本概念及编程(6)

[windriver@windriver-machine ltest]$ sed -n ''/north/p'' datafile
northwest NW Charles Main 3.0 .90 3 34
northeast NE AM Main Jr. 5.1 .94 3 13
north NO Margot Weber 4.5 .89 5 9
[windriver@windriver-machine ltest]$ sed ''/north/p'' datafile
northwest NW Charles Main 3.0 .90 3 34
northwest NW Charles Main 3.0 .90 3 34
western WE Sharon Gray 5.3 .97 5 23
southwest SW Lewis Dalsass 2.7 .8 2 18
southern SO Suan chin 5.1 .95 4 15
southeast SE Patricia 4.0 .7 4 17
eastern EA TB Savage 4.4 .84 5 20
northeast NE AM Main Jr. 5.1 .94 3 13
northeast NE AM Main Jr. 5.1 .94 3 13
north NO Margot Weber 4.5 .89 5 9
north NO Margot Weber 4.5 .89 5 9
central CT Ann Stephens 5.7 .94 5 13
[windriver@windriver-machine ltest]$ sed -n ''/north/p'' datafile
northwest NW Charles Main 3.0 .90 3 34
northeast NE AM Main Jr. 5.1 .94 3 13
north NO Margot Weber 4.5 .89 5 9
[windriver@windriver-machine ltest]$ sed ''/north/'' datafile
sed: -e expression #1, char 7: missing command
[windriver@windriver-machine ltest]$ sed -n ''/north/'' datafile
sed: -e expression #1, char 7: missing command
[windriver@windriver-machine ltest]$ sed ''3d'' datafile
northwest NW Charles Main 3.0 .90 3 34
western WE Sharon Gray 5.3 .97 5 23
southern SO Suan chin 5.1 .95 4 15
southeast SE Patricia 4.0 .7 4 17
eastern EA TB Savage 4.4 .84 5 20
northeast NE AM Main Jr. 5.1 .94 3 13
north NO Margot Weber 4.5 .89 5 9
central CT Ann Stephens 5.7 .94 5 13
[windriver@windriver-machine ltest]$ sed ''3,$d'' datafile
northwest NW Charles Main 3.0 .90 3 34
western WE Sharon Gray 5.3 .97 5 23
[windriver@windriver-machine ltest]$ sed ''$d'' datafile
northwest NW Charles Main 3.0 .90 3 34
western WE Sharon Gray 5.3 .97 5 23
southwest SW Lewis Dalsass 2.7 .8 2 18
southern SO Suan chin 5.1 .95 4 15
southeast SE Patricia 4.0 .7 4 17
eastern EA TB Savage 4.4 .84 5 20
northeast NE AM Main Jr. 5.1 .94 3 13
north NO Margot Weber 4.5 .89 5 9
[windriver@windriver-machine ltest]$ sed ''/north/d'' datafile
western WE Sharon Gray 5.3 .97 5 23
southwest SW Lewis Dalsass 2.7 .8 2 18
southern SO Suan chin 5.1 .95 4 15
southeast SE Patricia 4.0 .7 4 17
eastern EA TB Savage 4.4 .84 5 20
central CT Ann Stephens 5.7 .94 5 13

[windriver@windriver-machine ltest]$ sed ''s/[0-9][0-9]$/&.5/p'' datafile
northwest NW Charles Main 3.0 .90 3 34.5
northwest NW Charles Main 3.0 .90 3 34.5
western WE Sharon Gray

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