Siege Lion on the road (iii) Linux (14)---Check the contents of the file

Common commands: Cat, TAC, NL, more, less, head, tail, OD ...

First, directly view the contents of the file: Cat, TAC, NL <== All-in-one read

1. cat [-abentv] File name

Parameter description:

-N: Prints the travel number, along with a blank line number.

-B: Prints the travel number, but only blank lines are displayed.

-E: Displays the trailing newline character $.

-T: Displays [Tab] as ^t.

-V: Lists some special characters that are not visible.

-A: Equivalent to the-vet parameter.

2, TAC: The effect is opposite to cat, reverse display.

3, NL: Add line number printing.

Second, can flip view: more, less

1, more (one page to flip): for example, More/etc/man.config;

At the end there will be a cursor waiting for input:--more--(28%)

Keys that can be entered:

SPACEBAR: Turn down one page.

Enter key: Scrolls down one line.

/string: Queries the keyword "string" down.

: F <== immediately displays the file name and the number of rows currently displayed.

Q: Leave the more command now.

2, less (one page, one page turn, and more features, but more flexible than more): Less/etc/man.config

Keys that can be entered:

SPACEBAR: down one page.

PgDn: down one page.

PgUp: Up one page.

/string: Query "string" down.

? string: Query up.

N: Repeats the previous query.

N: Reverse repeats the previous query.

Q: Leave.

Third, data selection: Head, tail (in behavioral units)

1. Head [-N number]:

Head/etc/man.config; <== Displays the first 10 rows by default.

Head-n 20/etc/man.config;

Head-n -100/etc/man.config; <== displays all rows except the last 100 lines.

2, tail [-N number]:-N: The representative shows a few lines; -F: Indicates continuous detection of the new file content that follows.

Tail/etc/man.config; <== Displays the following 10 rows by default.

Tail-n 20/etc/man.config;

Tail-n +100/etc/man.config; <== displays all rows after 100 rows.

Tail-f/var/log/catalina.out;

Four, non-plain text files: od <== for binary files and so on.

od [-t TYPE] File

V. Modify the file time or create a new file: Touch

Understand the meaning of mtime (last modified time), CTime (state change time), Atime (time last Read).

1. Command format: Touch [-ACDMT] File

2. Parameter Description:

-A: Only the access time is modified.

-C: Modifies only the file's CTime and does not create a new file if the file does not exist.

-D: You can specify a date.

-M: Modifies only mtime.

-T: Time can be specified.

3. Example:

Touch test1; <== Create an empty file

touch-d "2 days Ago" test1; <== date adjusted to two days ago