| Character | Where | Meaning |
| ESC | csh | Filename completion. |
| RETURN | csh, sh | Execute command. |
| space | csh, sh | Argument separator. |
| TAB | csh, sh | Argument separator. |
| TAB | bash | Filename completion. |
| # | csh, sh | Start a comment. |
| ` | csh, sh | Command substitution (backquotes). |
| " | csh, sh | Weak quotes. |
| ' | csh, sh | Strong quotes. |
| \ | csh, sh | Single?character quote. |
| $var | csh, sh | Variable. |
| ${var} | csh, sh | Same as $var. |
| $var:mod | csh | Edit var with modifier mod |
| ${var?default} | sh | If var not set, use default. |
| ${var=default} | sh | If var not set, set it to default and use that value. |
| ${var+instead} | sh | If var set, use instead. Otherwise, null string. |
| ${var?message} | sh | If var not set, print message (else default). If var set, use its value. |
| ${var#pat} | ksh, bash | Value of var with smallest pat deleted from start. |
| ${var##pat} | ksh, bash | Value of var with largest pat deleted from start. |
| ${var%pat} | ksh, bash | Value of var with smallest pat deleted from end. |
| ${var%%pat} | ksh, bash | Value of var with largest pat deleted from end. |
| | | csh, sh | Pipe standard output. |
| |& | csh | Pipe standard output and standard error. |
| ^ | sh | Pipe character (obsolete). |
| ^ | csh, bash | Edit previous command line. |
| & | csh, sh | Run program in background. |
| ? | csh, sh | Match one character. |
| * | csh, sh | Match zero or more characters. |
| ; | csh, sh | Command separator. |
| ;; | sh | [/td]End of case statement.[/tr] |
| ~ | csh, ksh, bash | Home directory. |
| ~user | csh, ksh, bash | Home directory of user. |
| ! | csh, bash | Command history. |
| - | Programs | Start of optional argument. |
| - | Programs | Read standard input. (Only certain programs.) |
| $# | csh, sh | Number of arguments to script. |
| "$@" | sh | Original arguments to script. |
| $* | csh, sh | Arguments to script. |
| $- | sh | Flags set in shell. |
| $? | sh | Status of previous command. |
| $$ | csh, sh | Process identification number. |
| $! | sh | Process identification number of last background job. |
| $< | csh | Read input from terminal. |
| cmd1 && cmd2 | csh, sh | Execute cmd2 if cmd1 succeeds. |
| cmd1 || cmd2 | csh, sh | Execute cmd2 if cmd1 succeeds. |
| $(..) | ksh, bash | Command substitution. |
| ((..)) | ksh, bash | Arithmetic evaluation. |
| \. file | sh | Execute commands from file in this shell. |
| : | sh | Evaluate arguments, return true. |
| : | sh | Separate values in paths. |
| : | csh | Variable modifier. |
| [] | csh, sh | Match range of characters. |
| [] | sh | Test. |
| %job | csh, ksh, bash | Identify job number. |
| (cmd;cmd) | csh, sh | Run cmd;cmd in a subshell. |
| {} | csh, bash | In?line expansions. |
| {cmd;cmd;} | sh | Like (cmd;cmd) without a subshell. |
| >file | csh, sh | Redirect standard output. |
| >>file | csh, sh | Append standard output. |
| csh, sh | Redirect standard input. | |
<| csh, sh | Read until word, do command and variable substitution. | |
| <<\word | csh, sh | Read until word, no substitution. |
| sh | Read until word, ignoring leading TABs. |
| >>! file | csh, sh | Append to file, even if noclobber set and file doesn't exist. |
| >! file | csh | Output to file, even if noclobber set and file exists. |
| >| file | ksh, bash | Output to file, even if noclobber set and file exists. |
| >& file | csh | Redirect standard output and standard error to file. |
| m> file | sh | Redirect output file descriptor m to file. |
| m>> file | sh | Append output file descriptor m to file. |
| m< file | sh | Redirect input file descriptor m from file. |
| <&m | sh | Take standard input from file descriptor m. |
| <&? | sh | Close standard input. |
| >&m | sh | Use file descriptor m as standard output. |
| >&- | sh | Close standard output. |
| m<&n | sh | Connect input file descriptor n to file descriptor m. |
| m<&- | sh | Close input file descriptor m. |
| n>&m | sh | Connect output file descriptor n to file descriptor m. |
| m>&- | sh | Close output file descriptor m. |
