Return the contents of a given FILE or concatenated FILE(s) to standard output.

• -n, --number : number all output lines.
• -E, --show-ends : display $ at end of each line.
• -T, --show-tabs : display TAB characters as ^I

 const cat = $.cat `-nE src/*.ts` // UnixExtension<string>

Change the current directory to DIR. Change to the previous directory using the - or $OLDPWD variable. If no stdin is supplied or -, change to HOME directory.

 $.cd `src`
 $.cd `$OLDPWD/dist`

Change the mode of each FILE to MODE. If reference option is supplied, change the mode of each FILE to that of RFILE.

• -c, --changes : report only when a change is made.
• --reference=RFILE : use RFILE's mode instead of MODE values.
• -R, --recursive : change files and directories recursively.

 $.chmod `755 build.sh`
 $.chmod `-R a=rwx dist`
 $.chmod `--reference test.sh build.sh`

Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY.

• -b, --backup : make a backup of each existing destination file.
• -S, --suffix=SUFFIX : override the usual backup suffix (~).
• -l, --dereference : always follow symbolic links in SOURCE.
• -p, --no-dereference : never follow symbolic links in SOURCE.
• -r, -R, --recursive : copy directories recursively.
• -u, --update : copy only when the SOURCE file is newer than the destination file or when the destination file is missing.

 $.cp `test.ts src`
 $.cp `test.ts test1.ts src`
 $.cp `-rbS BACKUP_ build src` // backup suffix = BACKUP_

Display the list of currently remembered directories. Add the directory stack using the pushd command and back up with the popd command.

• -c : clear the directory stack by deleting all of the elements.

Arguments:

• +N : Displays the Nth entry counting from the left of the list when invoked without options, starting with zero.
• N : Displays the Nth entry counting from the right of the list when invoked without options, starting with zero.

 const dirs = $.dirs `` // UnixExtension<string[]> 
 
 $.dirs `-c`
 $.dirs `+3`

Echo the STRING(s) to standard output and print it.

• -n : do not output the trailing newline.

 const echo = $.echo `Hello World!` // UnixExtension<string>
 $.echo `Print`

Search for PATTERN(REGEX) in each FILE.

• -i, --ignore-case : ignore case distinctions in patterns and data.
• -v, --invert-match : select non-matching lines.
• -n, --line-number : print line number with output lines.
• -H, --with-filename : print file name with output lines.
• -r, --recursive : read all files under each directory, recursively.
• -l, --files-with-matches : print only names of FILEs with selected lines.

 const grep = $.grep `-i ^import src/*.ts` // UnixExtension<string[]>

Print the first 10 lines of each FILE to standard output. If multiple files are supplied, prepend each with a header indicating the file name.

• -c, --bytes=NUM : print the first NUM bytes of each file
• -n, --lines=NUM : print the first NUM lines instead of the first 10.
• -q, --quiet, --silent : never print headers giving file names.

 const head = $.head `-n 15 src/test.ts` // UnixExtension<string>
 
 $.head `-c 100 src/test.ts`
 $.head `-q src/*.ts`

By default, create hard link from SOURCE to DEST. If -s or --symbolic option is supplied, create symbolic link.

• -b, --backup : make a backup of each existing destination file.
• -f, --force : remove existing destination files.
• -s, --symbolic : make symbolic links instead of hard links.
• -S, --suffix=SUFFIX : override the usual backup suffix(~).

 $.ln `file link`
 $.ln `-bS BACKUP_ file exist` // backup suffix = BACKUP_

List information about the FILE(s). If FILE is not supplied, list information about the current directory.

• -a, --all : do not ignore entries starting with ..
• -A, --almost-all : do not list implied . and ...
• -d, --directory : list directories themselves, not their contents.
• -l : use a long listing format.
• -L, --dereference : show information for the file the link references rather than for the link itself.
• -r, --reverse : reverse order while sorting.
• -R, --recursive : list subdirectories recursively.

 const ls = $.ls `-al`
 
 $.ls `-R src dist`
 $.ls `-l src/**/*.ts`

Create the DIRECTORY(ies), if they do not already exist.

• -m, --mode=MODE : set file mode (must be octal - unmask).
• -p, --parents : no error if existing, make parent directories as needed.

 $.mkdir `test test1`
 $.mkdir `-m 777 test`
 $.mkdir `-p test/test1` // if 'test' is not exist, make it.

Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY.

• -b, --backup : make a backup of each existing destination file.
• -S, --suffix=SUFFIX : override the usual backup suffix(~).

 $.mv `file file_renamed`
 $.mv `file file1 dir` // rename to 'dir/file', 'dir/file1'.

Remove directories from stack. If no arguments are supplied, remove the top directory from the stack, and changes to the new top directory.

• -n : Suppresses the normal change of directory when removing directories from the stack, so only the stack is manipulated.

Arguments:

• +N : Removes the Nth entry counting from the left of the list, starting with zero.
• N : Removes the Nth entry counting from the right of the list, starting with zero.

 const popd = $.popd `` // UnixExtension<string[]> - directory stack.
 $.popd `-n`
 $.popd `+3`

Add directories to stack. If no arguments are supplied, exchanges the top two directories.

• -n : Suppresses the normal change of directory when adding directories to the stack, so only the stack is manipulated.

Arguments:

• +N : Rotates the stack so that the Nth directory counting from the left of the list, starting with zero is at the top.
• N : Rotates the stack so that the Nth directory counting from the right of the list, starting with zero is at the top.
• DIR : Adds DIR to the directory stack at the top, making it the new current working directory.

 const pushd = $.pushd `` // UnixExtension<string[]> - directory stack.
 $.pushd `-n hello`
 $.pushd `dir`

Print the name of the current working directory.

 const pwd = $.pwd `` // UnixExtension<string>

Remove (unlink) the FILE(s).

• -f, --force : ignore nonexistent files and arguments, never prompt.
• -r, --recursive : remove directories and their contents recursively.

 $.rm `file`
 $.rm `file file1 file2`
 $.rm `-rf dir`

Remove the DIRECTORY(ies), if they are empty.

• -p, --parents : remove DIRECTORY and its ancestors; rmdir -p a/b/c -> rmdir a/b/c a/b a

 $.rmdir `dir`
 $.rmdir `-p parent/dir`

Set or unset, change the value of shell variables and attributes. If no arguments or options are supplied, display the names and values of shell variables. Using + rather than - causes these flags to be turned off.

• -f : Disable file name generation (globbing).
• -v : Print shell input lines as they are read(verbose).
• -C : If set, disallow existing regular files to be overwritten by redirection(>) of output.

 const set = $.set ``
 
 $.set `-fC`
 $.set `+f`
 $.set `var1=value`

Pause for NUMBER seconds. SUFFIX may be 's' for seconds (default), 'm' for minutes, 'h' for hours or 'd' for days.

 $.sleep `5`  // 5 seconds
 $.sleep `5m` // 5 minutes

Write sorted concatenation of all FILE(s) to standard output.

• -f, --ignore-case : fold lower case to upper case characters.
• -n, --numeric-sort : compare according to string numerical value.
• -r, --reverse : reverse the result of comparisons.

 const sort = $.sort `-f file` // UnixExtension<string>
 $.sort `-r *.ts file`

Print the last 10 lines of each FILE to standard output. If multiple files are supplied, prepend each with a header indicating the file name.

• -c, --bytes=NUM : output the last NUM bytes; or use +NUM to output starting with byte NUM of each file.
• -n, --lines=NUM : output the last NUM lines, instead of the last 10; or use +NUM to output starting with line NUM.
• -q, --quiet, --silent : never print headers giving file names.

 const tail = $.tail `-n 15 src/test.ts` // UnixExtension<string>
 
 $.tail `-n +15 src/test.ts`
 $.tail `*.ts files`

Update the access and modification times of each FILE to the current time. A FILE argument that does not exist is created empty unless -c option is supplied.

• -a : change only the access time.
• -c, --no-create : do not create any files.
• -d, --date=STRING : parse STRING and use it instead of current time.
• -m : change only the modification time.
• -r, --reference=RFILE : use this RFILE's times instead of current time.

 $.touch `not_exist.js`     // create 'not_exist.js'
 $.touch `exist.js`         // change access and modification times.
 $.touch `-r file exist.js` // change times of 'exist.js' to 'file's time.
 $.touch `-d 1234-03-21 exist.js` // change times of 'exist.js' to Mar 21, 1234

Filter adjacent matching lines from INPUT, writing to OUTPUT or standard output.

• -c, --count : prefix lines by the number of occurrences.
• -d, --repeated : only print duplicate lines, one for each group.
• -i, --ignore-case : ignore differences in case when comparing.

 const uniq = $.uniq `-c file`
 
 $.uniq `file output` // write to 'output'.

Each environment variable specified by name shall be unset.

 $.set `user=Test pass=1234` 
 $.unset `user pass`

Search an executable or script in the directories listed in the environment variable PATH and print full path to standard output.

• -a, --all : Print all matching executables in PATH, not just the first.

 const which = $.which `git` // UnixExtension<string>
 $.which `-a node`

Print the user name associated with the current effective user ID.

 const user = $.whoami `` // UnixExtension<string>