KShell

KShell Namespace Reference

Typedefs

typedef QFlags< OptionOptions
 

Enumerations

enum  Errors { NoError = 0, BadQuoting, FoundMeta }
 
enum  Option { NoOptions = 0, TildeExpand = 1, AbortOnMeta = 2 }
 

Functions

KCOREADDONS_EXPORT QString joinArgs (const QStringList &args)
 
KCOREADDONS_EXPORT QString quoteArg (const QString &arg)
 
KCOREADDONS_EXPORT QStringList splitArgs (const QString &cmd, Options flags=NoOptions, Errors *err=nullptr)
 
KCOREADDONS_EXPORT QString tildeCollapse (const QString &path)
 
KCOREADDONS_EXPORT QString tildeExpand (const QString &path)
 

Detailed Description

Emulates some basic system shell functionality.

See also
KStringHandler

Typedef Documentation

Stores a combination of Option values.

Definition at line 73 of file kshell.h.

Enumeration Type Documentation

Status codes from splitArgs()

Enumerator
NoError 

Success.

BadQuoting 

Indicates a parsing error, like an unterminated quoted string.

FoundMeta 

The AbortOnMeta flag was set and an unhandled shell meta character was encountered.

Definition at line 79 of file kshell.h.

Flags for splitArgs().

See also
Options
Enumerator
TildeExpand 

Perform tilde expansion.

On Windows, this flag is ignored, as the Windows shell has no equivalent functionality.

AbortOnMeta 

Put the parser into full shell mode and bail out if a too complex construct is encountered.

A particular purpose of this flag is finding out whether the command line being split would be executable directly (via KProcess::setProgram()) or whether it needs to be run through a real shell (via KProcess::setShellCommand()). Note, however, that shell builtins are not recognized - you need to do that yourself (compare with a list of known commands or verify that an executable exists for the named command).

Meta characters that cause a bail-out are the command separators semicolon and ampersand, the redirection symbols less-than, greater-than and the pipe symbol and the grouping symbols opening and closing parentheses.

Further meta characters on *NIX are the grouping symbols opening and closing braces, the command substitution symbol backquote, the generic substitution symbol dollar (if not followed by an apostrophe), the wildcards asterisk, question mark and opening and closing square brackets and the comment symbol hash mark. Additionally, a variable assignment in the first word is recognized.

A further meta character on Windows is the environment variable expansion symbol percent. Occurrences of %PERCENT_SIGN% as inserted by quoteArg() are converted back and cause no bail-out, though.

Definition at line 29 of file kshell.h.

Function Documentation

QString KShell::joinArgs ( const QStringList args)

Quotes and joins args together according to system shell rules.

If the output is fed back into splitArgs(), the AbortOnMeta flag needs to be used on Windows. On *NIX, no such requirement exists.

See quoteArg() for more info.

Parameters
argsa list of strings to quote and join
Returns
a command suitable for shell execution

Definition at line 23 of file kshell.cpp.

QString KShell::quoteArg ( const QString arg)

Quotes arg according to system shell rules.

This function can be used to quote an argument string such that the shell processes it properly. This is e.g. necessary for user-provided file names which may contain spaces or quotes. It also prevents expansion of wild cards and environment variables.

On *NIX, the output is POSIX shell compliant. On Windows, it is compliant with the argument splitting code of the Microsoft C runtime and the cmd shell used together. Occurrences of the percent sign are replaced with %PERCENT_SIGN% to prevent spurious variable expansion; related KDE functions are prepared for this.

Parameters
argthe argument to quote
Returns
the quoted argument

Definition at line 297 of file kshell_unix.cpp.

QStringList KShell::splitArgs ( const QString cmd,
Options  flags = NoOptions,
Errors err = nullptr 
)

Splits cmd according to system shell word splitting and quoting rules.

Can optionally perform tilde expansion and/or abort if it finds shell meta characters it cannot process.

On *NIX the behavior is based on the POSIX shell and bash:

  • Whitespace splits tokens
  • The backslash quotes the following character
  • A string enclosed in single quotes is not split. No shell meta characters are interpreted.
  • A string enclosed in double quotes is not split. Within the string, the backslash quotes shell meta characters - if it is followed by a "meaningless" character, the backslash is output verbatim.
  • A string enclosed in $'' is not split. Within the string, the backslash has a similar meaning to the one in C strings. Consult the bash manual for more information.

On Windows, the behavior is defined by the Microsoft C runtime. Qt and many other implementations comply with this standard, but many do not.

  • Whitespace splits tokens
  • A string enclosed in double quotes is not split
    • 2N double quotes within a quoted string yield N literal quotes. This is not documented on MSDN.
  • Backslashes have special semantics iff they are followed by a double quote:
    • 2N backslashes + double quote => N backslashes and begin/end quoting
    • 2N+1 backslashes + double quote => N backslashes + literal quote

If AbortOnMeta is used on Windows, this function applies cmd shell semantics before proceeding with word splitting:

  • Cmd ignores all special chars between double quotes. Note that the quotes are not removed at this stage - the tokenization rules described above still apply.
  • The circumflex is the escape char for everything including itself.
Parameters
cmdthe command to split
flagsoperation flags, see Option
errif not NULL, a status code will be stored at the pointer target, see Errors
Returns
a list of unquoted words or an empty list if an error occurred

Definition at line 58 of file kshell_unix.cpp.

QString KShell::tildeCollapse ( const QString path)

Performs tilde collapse on path.

If path did not start by the user homedir returns path unchanged.

Parameters
paththe path to tilde-collpase
Returns
the collapsed path
Since
5.67

Definition at line 59 of file kshell.cpp.

QString KShell::tildeExpand ( const QString path)

Performs tilde expansion on path.

Interprets "~/path" and "~user/path". If the path starts with an escaped tilde ("\~" on UNIX, "^~" on Windows), the escape char is removed and the path is returned as is.

Note that if path starts with a tilde but cannot be properly expanded, this function will return an empty string.

Parameters
paththe path to tilde-expand
Returns
the expanded path

Definition at line 41 of file kshell.cpp.

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