Editing Linux commands (section)

=== List directory or files /  list directory contents ===
* ls ({{Linux}}) [http://linuxcommand.org/man_pages/ls1.html    ls - list directory contents]
** List detailed information of files. e.g. {{kbd | key= ls -lh}}<ref>[http://linux.vbird.org/linux_basic/0210filepermission.php 鳥哥的 Linux 私房菜 -- Linux 的檔案權限與目錄配置]</ref> <ref>[OPTION]
* -l use a long listing format
* -h, --human-readable; with -l, print sizes in human readable format (e.g., 1K 234M 2G) Quoted from linux {{kbd | key=man ls}}</ref> 
** List detailed information of files and sort by modification time. {{kbd | key= ls -lht}}
** List top N files and sort by modification time. {{kbd | key= <nowiki>ls -lht | head -N</nowiki>}} e.g. {{kbd | key= <nowiki>ls -lht | head -10</nowiki>}} First line is the total file size of specified folder.<ref>[http://www.unix.com/unix-for-dummies-questions-and-answers/44493-how-list-top-10-files.html How to list top 10 files | Unix Linux Forums | UNIX for Dummies Questions & Answers]</ref>
* ll  ({{Linux}}) {{kbd | key= ll}} = {{kbd | key= ls -l}}
* Print the entire path of files and '''level-unlimited''' sub-directories in the current directory. On {{Win}} using {{kbd | key= dir/s/b}}, and on {{Linux}} using {{kbd | key= find /path/to/files/ -print}} <ref>[http://superuser.com/questions/159975/making-ls-output-like-dir-b-s linux - Making ls output like dir /b /s - Super User]</ref>.
* {{Gd}}  create ls command in {{Win}} command prompt: {{kbd | key = echo dir %1 > %systemroot%\system32\ls.bat}} Thanks, hmjd!<ref>[http://stackoverflow.com/questions/9362692/how-to-create-ls-in-windows-command-prompt How to create ls in windows command prompt? - Stack Overflow]</ref>
* List all files and directories including hidden ones in the current directory. On {{Win}} is {{kbd | key=<nowiki>dir /a</nowiki>}}, and on {{Mac}} or {{Linux}} is {{kbd | key=<nowiki>ls -a</nowiki>}}<ref>[http://www.computerhope.com/issues/ch001039.htm How to see hidden files in MS-DOS and the Command Prompt]</ref><ref>[http://www.cyberciti.biz/faq/bash-shell-display-only-hidden-dot-files/ Bash Shell: Display All Hidden Dot Files In a Directory]</ref>.

List only filenames and one file per line
* {{Win}} {{kbd | key=dir/b}}<ref>[https://smallbusiness.chron.com/copy-list-files-windows-folder-excel-list-40032.html How to Copy a List of Files in a Windows Folder Into an Excel List]</ref>
* {{Mac}} {{kbd | key=ls -1}}<ref>[https://www.baeldung.com/linux/list-one-filename-per-line List One Filename Per Line in Linux | Baeldung on Linux]</ref>


Verify if a file or a directory exists
* On {{Linux}}: {{kbd | key= ls /path/to/file}} or {{kbd | key= ls -d /path/to/directory/}} e.g. {{kbd | key= ls -d ~/}} to list your home directory<ref>[https://linuxconfig.org/single-linux-command-to-return-to-home-directory Single linux command to return to home directory]</ref>.
* On {{Win}}: 
** {{kbd | key= dir C:\path\to\file}} or {{kbd | key= dir C:\path\to\directory\}}
** {{kbd | key= IF EXIST}} <ref>[http://stackoverflow.com/questions/3022176/how-to-verify-if-a-file-exists-in-a-windows-bat-file How to verify if a file exists in a Windows .BAT file? - Stack Overflow]</ref><ref>[http://stackoverflow.com/questions/2903416/windows-shell-string-operations-changing-backslash-to-slash Windows shell string operations (changing backslash to slash) - Stack Overflow]</ref>

<pre>
SET a=C:\path\to\file
REM -- If the directory was separated the \ symbol & the path NOT contains space
IF EXIST %a% (ECHO YES) ELSE (ECHO No)

SET a="C:\path\to\directory contains space\space"
REM -- If the directory was separated the \ symbol & the path contains space
IF EXIST %a% (ECHO YES) ELSE (ECHO No)

SET a=C:/path/to/file
REM -- If the directory was separated the / symbol, the next command replace / with \ symbol.
SET a=%a:/=\%
IF EXIST %a% (ECHO YES) ELSE (ECHO No)
</pre>

troubleshooting
<pre>
SET a = C:\path\to\file
REM -- Correct command: SET a=C:\path\to\file
IF EXIST %a% (ECHO YES) ELSE (ECHO No)
REM -- the returned result will not correct!
</pre>