8.10 Shell special symbol cut command
8.11 sort_wc_uniq command
8.12 tee_tr_split command
8.13 Under special shell symbols
8.10 Shell special symbol cut command
Summarize special symbols
Examples of \ escape characters:
cut cuts a string. Example: Use the pipe character head to find out the first two paragraphs, and then do an interception.
8.11 sort_wc_uniq command
sort sort (usually used in conjunction with uniq)
sort /etc/passwd The normal first line is root and now it is displayed in the order of abc. (sorted by Asma by default)
head /etc/passwd >>1.txt
vim1.txt, add a few more lines of numbers and special symbols, and then sort 1.txt
Special symbols come first, then numbers, then letters.
sort -n (to sort by numbers, letters or special symbols will be regarded as zeros in front.)
sort -r (sort in reverse)
sort -t (specify the delimiter, just understand it)
wc -l counts the number of lines -m counts the number of characters (newlines are also counted) -w counts the words (one word, separated by spaces)
uniq (de-duplication is conditional. It needs to be sorted first and then de-duplicated, otherwise it will be invalid)
uniq -c count the number of repetitions // basically used in combination with sort, sort first and then deduplicate sort 1.txt|uniq
(commands like sort and uniq do not change the content)
8.12 tee_tr_split command
tee like > (output redirection)
比如sort 2.txt |uniq -c |tee a.txt
The role of |tee is to redirect, and the redirected content will be displayed below (> the content will not be displayed)
tee -a like >> (append)
tr (replace)
And you can specify the range [az] into [AZ] is to turn all letters into uppercase.
split is used to view some large files, such as very large logs.
split -b specifies the size
split -l specifies the number of lines
It is possible to specify a name while cutting, but it is only a prefix. split -l 100k a.txt aaa
8.13 Under special shell symbols
$! indicates the end of the previous line
;For writing multiple commands in one line;Split
&>: Both true and false output redirection.
|| means or for example ls 1.txt || ls 2.txt (if the first item is unsuccessful, the second item will be executed, and if the first item is successful, the second item will not be executed)
&& The next command will only be executed if the previous command is executed successfully.