cse15l-lab-reports

Week 9 Lab Report: Researching More Commands

ls command

The following are 4 interesting command-line options for the ls command:

• -m fill width with a comma separated list of entries
• -l use a long listing format
• -a do not ignore entries starting with . (hidden files)
• -t sort by time (newest first)

I found all of these on the ls man page on man7.org

Here are some examples of using these command-line options on files and directories from the src folder in Scenario 4 of week 9’s lab

-m

$ ls -m
java, tests, textfiles

This ls -m command separates the 3 subdirectories with a comma as opposed to displaying them in columns.

$ cd java
$ ls -m
Code.class, Code.java

Like above, the -m here separates the 2 files with a comma.

-l

$ cd ..
$ ls -l
total 0
drwxr-xr-x  5 vivianliu  staff  160 Mar  9 14:14 java
drwxr-xr-x  4 vivianliu  staff  128 Mar  9 10:36 tests
drwxr-xr-x  4 vivianliu  staff  128 Mar  9 10:38 textfiles

This command uses a long listing format, displaying each subdirectory on its own line. We can see that it gives additional information such as the time of last modification.

$ cd tests
$ ls -l
total 16
-rw-r--r--  1 vivianliu  staff  53 Mar  9 10:37 CodeTests1.java
-rw-r--r--  1 vivianliu  staff  53 Mar  9 10:37 CodeTests2.java

Like the previous example, the -l displays everything in long listing format.

-a

$ cd ../java
$ ls -a
.		..		.gitignore	Code.class	Code.java

I added a .gitignore file to the java directory. The -a is important here because otherwise the .gitignore file wouldn’t be shown.

$ ls -al
total 24
drwxr-xr-x  5 vivianliu  staff  160 Mar  9 14:14 .
drwxr-xr-x  5 vivianliu  staff  160 Mar  9 10:38 ..
-rw-r--r--  1 vivianliu  staff    7 Mar  9 14:14 .gitignore
-rw-r--r--  1 vivianliu  staff  569 Mar  9 10:39 Code.class
-rw-r--r--  1 vivianliu  staff  303 Mar  9 10:46 Code.java

This example shows the power of combining multiple command-line arguments. I combined -a with -l, which displays everything, including hidden files, in long listing format.

-t

$ -alt
total 24
-rw-r--r--  1 vivianliu  staff    7 Mar  9 14:14 .gitignore
drwxr-xr-x  5 vivianliu  staff  160 Mar  9 14:14 .
-rw-r--r--  1 vivianliu  staff  303 Mar  9 10:46 Code.java
-rw-r--r--  1 vivianliu  staff  569 Mar  9 10:39 Code.class
drwxr-xr-x  5 vivianliu  staff  160 Mar  9 10:38 ..

This is the same as the above example, except I added a -t so it now lists all the files and directories based on the time they were last modified (newest first).

$ cd ..
$ ls -altr
total 0
drwxr-xr-x  4 vivianliu  staff  128 Mar  9 10:36 tests
drwxr-xr-x  5 vivianliu  staff  160 Mar  9 10:38 .
drwxr-xr-x  4 vivianliu  staff  128 Mar  9 10:38 textfiles
drwxr-xr-x  3 vivianliu  staff   96 Mar  9 11:03 ..
drwxr-xr-x  5 vivianliu  staff  160 Mar  9 14:14 java

Once again, -t lists everything based on the time they were last modified. I also added an -r option here, which lists everything from oldest to newest instead.