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Shell-related Utilities

Shell-related Utilities — shell-like commandline handling

Types and Values

enum GShellError


#include <glib.h>


GLib provides the functions g_shell_quote() and g_shell_unquote() to handle shell-like quoting in strings. The function g_shell_parse_argv() parses a string similar to the way a POSIX shell (/bin/sh) would.

Note that string handling in shells has many obscure and historical corner-cases which these functions do not necessarily reproduce. They are good enough in practice, though.


g_shell_parse_argv ()

g_shell_parse_argv (const gchar *command_line,
                    gint *argcp,
                    gchar ***argvp,
                    GError **error);

Parses a command line into an argument vector, in much the same way the shell would, but without many of the expansions the shell would perform (variable expansion, globs, operators, filename expansion, etc. are not supported). The results are defined to be the same as those you would get from a UNIX98 /bin/sh, as long as the input contains none of the unsupported shell expansions. If the input does contain such expansions, they are passed through literally. Possible errors are those from the G_SHELL_ERROR domain. Free the returned vector with g_strfreev().



command line to parse.

[type filename]


return location for number of args.



return location for array of args.

[out][optional][array length=argcp zero-terminated=1][element-type filename]


return location for error.



TRUE on success, FALSE if error set

g_shell_quote ()

gchar *
g_shell_quote (const gchar *unquoted_string);

Quotes a string so that the shell (/bin/sh) will interpret the quoted string to mean unquoted_string . If you pass a filename to the shell, for example, you should first quote it with this function. The return value must be freed with g_free(). The quoting style used is undefined (single or double quotes may be used).



a literal string.

[type filename]


quoted string.

[type filename]

g_shell_unquote ()

gchar *
g_shell_unquote (const gchar *quoted_string,
                 GError **error);

Unquotes a string as the shell (/bin/sh) would. Only handles quotes; if a string contains file globs, arithmetic operators, variables, backticks, redirections, or other special-to-the-shell features, the result will be different from the result a real shell would produce (the variables, backticks, etc. will be passed through literally instead of being expanded). This function is guaranteed to succeed if applied to the result of g_shell_quote(). If it fails, it returns NULL and sets the error. The quoted_string need not actually contain quoted or escaped text; g_shell_unquote() simply goes through the string and unquotes/unescapes anything that the shell would. Both single and double quotes are handled, as are escapes including escaped newlines. The return value must be freed with g_free(). Possible errors are in the G_SHELL_ERROR domain.

Shell quoting rules are a bit strange. Single quotes preserve the literal string exactly. escape sequences are not allowed; not even \' - if you want a ' in the quoted text, you have to do something like 'foo'\''bar'. Double quotes allow $, `, ", \, and newline to be escaped with backslash. Otherwise double quotes preserve things literally.



shell-quoted string.

[type filename]


error return location or NULL



an unquoted string.

[type filename]

Types and Values

enum GShellError

Error codes returned by shell functions.



Mismatched or otherwise mangled quoting.



String to be parsed was empty.



Some other error.



#define G_SHELL_ERROR g_shell_error_quark ()

Error domain for shell functions. Errors in this domain will be from the GShellError enumeration. See GError for information on error domains.

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