linux下，提取无重复字符串
目标=提取文件内容中的fileName，无重复。
------------------待处理文件
the follow code has no meaning, just for testing.
# exec copy $svr/c4.txt to $user/b1-dir
exec copy $svr/a4.txt to $user/b1-dir
#
try to extract information from a file using linux commands.
exec copy $svr/a3.txt to $user/b2-dir
exec copy $svr/a2.txt to $user/b3-dir
line test again;
exec copy $svr/a1.txt to $user/b4-dir
exec copy $svr/a9.txt to $user/b5-dir
exec copy $svr/a8.txt to $user/b6-dir
exec copy $svr/a7.txt to $user/b7-dir
# exec copy $svr/c5.txt to $user/b1-dir
exec copy $svr/a6.txt to $user/b8-dir
exec copy $svr/a5.txt to $user/b9-dir
paste file to another file test:
exec copy $svr/a4.txt to $user/b1-dir
exec copy $svr/a3.txt to $user/b2-dir
exec copy $svr/a2.txt to $user/b3-dir
exec copy $svr/a1.txt to $user/b4-dir
------------------待处理文件end
解答=
grep ".txt" test.txt | sed 's/# //' | cut -d ' ' -f3 | cut -d '/' -f2 | sort | uniq
解释=
grep ".txt" test.txt 提取含有".txt"的整行字符串。
sed 's/# //' 移除行首的注释符“# ”。
cut -d ' ' -f3 按' '分割每行，取出第3个子串。
cut -d '/' -f2 按'/'分割每行，取出第2个子串。
sort 对所有行排序。
uniq 剔除重复的行。
结果=
a1.txt
a2.txt
a3.txt
a4.txt
a5.txt
a6.txt
a7.txt
a8.txt
a9.txt
c4.txt
c5.txt